CN110148338A - A kind of electromagnetic induction experimental apparatus for researching and its experimental method - Google Patents

A kind of electromagnetic induction experimental apparatus for researching and its experimental method Download PDF

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CN110148338A
CN110148338A CN201910357642.XA CN201910357642A CN110148338A CN 110148338 A CN110148338 A CN 110148338A CN 201910357642 A CN201910357642 A CN 201910357642A CN 110148338 A CN110148338 A CN 110148338A
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coil
transformer
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binding post
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周平原
周培宇
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    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09B—EDUCATIONAL OR DEMONSTRATION APPLIANCES; APPLIANCES FOR TEACHING, OR COMMUNICATING WITH, THE BLIND, DEAF OR MUTE; MODELS; PLANETARIA; GLOBES; MAPS; DIAGRAMS
    • G09B23/00—Models for scientific, medical, or mathematical purposes, e.g. full-sized devices for demonstration purposes
    • G09B23/06—Models for scientific, medical, or mathematical purposes, e.g. full-sized devices for demonstration purposes for physics
    • G09B23/18—Models for scientific, medical, or mathematical purposes, e.g. full-sized devices for demonstration purposes for physics for electricity or magnetism
    • G09B23/181—Models for scientific, medical, or mathematical purposes, e.g. full-sized devices for demonstration purposes for physics for electricity or magnetism for electric and magnetic fields; for voltages; for currents
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09B—EDUCATIONAL OR DEMONSTRATION APPLIANCES; APPLIANCES FOR TEACHING, OR COMMUNICATING WITH, THE BLIND, DEAF OR MUTE; MODELS; PLANETARIA; GLOBES; MAPS; DIAGRAMS
    • G09B23/00—Models for scientific, medical, or mathematical purposes, e.g. full-sized devices for demonstration purposes
    • G09B23/06—Models for scientific, medical, or mathematical purposes, e.g. full-sized devices for demonstration purposes for physics
    • G09B23/18—Models for scientific, medical, or mathematical purposes, e.g. full-sized devices for demonstration purposes for physics for electricity or magnetism
    • G09B23/183—Models for scientific, medical, or mathematical purposes, e.g. full-sized devices for demonstration purposes for physics for electricity or magnetism for circuits

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Abstract

A kind of electromagnetic induction experimental apparatus for researching and its experimental method, belong to pedagogical model technical field, including transformer, ammeter, small bulbs, rheostat, low-tension supply, A.C. voltmeter, switch；The transformer includes first coil, the second coil and tertiary coil；The first binding post and the second binding post is respectively set in the first coil both ends；Third binding post and the 4th binding post is respectively set in second coil both ends；The 5th binding post and the 6th binding post is respectively set in the tertiary coil both ends.The technical program utilizes better simply device quantitative verification Faraday's electromagnetic induction law, can complete the relevant some experiments of electromagnetic induction, work well, cost is also low；The technical program further solves the problems, such as physics experiments of high school, the preferably physics experiment ability of training student.

Description

A kind of electromagnetic induction experimental apparatus for researching and its experimental method
Technical field
The invention belongs to pedagogical model technical fields, and in particular to be a kind of electromagnetic induction experimental apparatus for researching and its experiment Method.
Background technique
Faraday's electromagnetic induction law is an important law of high school physics, but in field research, is limited to middle school's reality The condition for testing room is difficult to carry out quantitative verification, and teacher can only directly introduce Faraday's electromagnetic induction law in conjunction with History of Physics, no Conducive to the understanding and grasp of student.
Self-inductance power experiment probes into the voltage at transformer coil both ends and the relationship experiments of the number of turns, imitates Faraday's reality It tests, demonstrate the experiment that inductance is all high school physics classics to inhibition experiment of alternating current etc., " probe into transformer coil both ends Voltage and the number of turns relationship " experiment more by teaching material arrangement be student experimenting.
But in the field research of school, these experiments all have that more or less or experiment effect is bad, or Person's experiment is not deep enough, not comprehensive enough.And the student experimenting that this needs everybody to start is to perform practically no function in most schools, it is main Want the reason is that, the experimental result obtained with school's equipment (transformer) differs too big with theoretical expectation values.
Therefore, it is necessary to modify and way of extensive experimentation function to experimental program, it is therefore an objective to further solve high school physics Experiment problem, the preferably physics experiment ability of training student.
Summary of the invention
It is an object of the invention to overcome defect and deficiency mentioned above, and provide a kind of electromagnetic induction experimental apparatus for researching And its experimental method.
The present invention realizes its purpose, and the technical solutions adopted are as follows.
A kind of electromagnetic induction experimental apparatus for researching and its experimental method, including it is transformer, ammeter, small bulbs, rheostat, low Voltage source, A.C. voltmeter, switch；The transformer includes that first coil, the second coil and tertiary coil, the number of turns are respectively n1、n2、n3, n1Greater than n3Greater than n2；The first binding post and the second binding post is respectively set in the first coil both ends；Described second Third binding post and the 4th binding post is respectively set in coil both ends；The 5th binding post and is respectively set in the tertiary coil both ends Six binding posts；The low-tension supply (5) is a kind of AC and DC low-tension supply or independent low-voltage alternating current power supply and independence Low-voltage dc power supply combination.
A coil in the low-tension supply, switch, rheostat and transformer connects to form series circuit；The ammeter It connects to form series circuit with one coil of residue of transformer；The low-tension supply is low-voltage dc power supply.
The first coil of the transformer or the second coil or tertiary coil, shape of connecting with small bulbs, switch, low-tension supply At closed circuit.
After the small bulbs are in parallel with the first coil of transformer or the second coil or tertiary coil with low tension subject string Connection；The low-tension supply is low-voltage dc power supply.
The small bulbs are in parallel with the first coil of transformer or the second coil or tertiary coil after connecting with rheostat, then It connects with low-tension supply, the low-tension supply is low-voltage dc power supply.
The different resistive values of the first coil, the second coil and tertiary coil are less big, select one of line every time When circle is connected into closed circuit with ammeter, the all-in resistance of three closed circuits is approximately equal, and difference is no more than 20%.
A kind of experimental method of electromagnetic induction experimental apparatus for researching, comprising the following steps:
A coil in the low-tension supply, switch, rheostat and transformer connects to form closed circuit, the ammeter and change One coil of residue of depressor connects to form another closed circuit, and the low-tension supply is low-voltage dc power supply；
The first step, the low-voltage dc power supply, switch, rheostat, transformer first coil connect to form closed circuit；Variable resistance The slide plate of device is placed in the larger position of resistance value, and the tertiary coil of transformer connects to form closed circuit with ammeter；
Second step, closure switch, while observing the full-scale reading (deflection reading) of ammeter and recording；
Third step disconnects switch, while observing the full-scale reading and record of ammeter；
4th step, rheostatic slide plate position remain unchanged, and by the second coil group of ammeter and transformer at series circuit, close Combination switch, while observing the full-scale reading of ammeter and the full-scale reading of ammeter in second step experimental implementation compares；
5th step disconnects switch, while observing the full-scale reading of ammeter, reads with the maximum of ammeter in third step experimental implementation Number compares；
Method of this experiment can also slightly be made and change, for example, the of the low-voltage dc power supply, switch, rheostat, transformer Two coil connects to form closed circuit, the first tertiary coil composition series circuit with transformer of ammeter, by electric current in the 4th step The first coil of table and transformer forms series circuit；For another example, the low-voltage dc power supply, switch, rheostat, transformer Tertiary coil connects to form the scheme of closed circuit；If transformer coil resistance value is larger, rheostat can be omitted.
A kind of experimental method of electromagnetic induction experimental apparatus for researching, comprising the following steps:
The first coil of the transformer or the second coil or tertiary coil, are connected into closure with small bulbs, switch, low-tension supply Circuit；
The first step, the first coil of transformer is connected with small bulbs, closure switch to be followed by low-voltage dc power supply；
Second step, closure switch observe small bulbs luminous situation；
Third step disconnects switch, and low-voltage dc power supply changes the approximately equal low-voltage alternating current power supply of voltage into, re-closes switch, Observe small bulbs luminous situation；
4th step, A.C. voltmeter measurement range selection exchange 20V, measure the voltage at small bulbs both ends, observe showing for A.C. voltmeter Number；
5th step changes first coil into tertiary coil, repeats step 1 to four.
6th step changes tertiary coil into second coil, repeats step 1 to four.
A kind of experimental method of electromagnetic induction experimental apparatus for researching, comprising the following steps:
It connects after the small bulbs are in parallel with the first coil of transformer or the second coil or tertiary coil with low-tension supply, institute Stating low-tension supply is low-voltage dc power supply；
The first step connects small bulbs with after the parallel connection of the first coil of transformer with low-tension supply；
Second step, closure switch observe the brightness of small bulbs；
Third step, disconnects switch, and observation disconnects moment small bulbs luminous situation；
Coil in circuit is changed into the tertiary coil of transformer by the 4th step, repeats to test；
Coil in circuit is changed into the second coil of transformer by the 5th step, repeats to test.
A kind of experimental method of electromagnetic induction experimental apparatus for researching, comprising the following steps:
The small bulbs are in parallel with the first coil of transformer or the second coil or tertiary coil after connecting with rheostat, then with it is low Piezoelectricity is source-series, and the low-tension supply is low-voltage dc power supply；
The first step, by small bulbs it is in parallel with the first coil of transformer after it is source-series with low-voltage DC；
Second step, closure switch observe the brightness of small bulbs；
Third step, disconnects switch, and observation disconnects moment small bulbs luminous situation；
4th step, it is in parallel with the first coil of transformer after small bulbs are connected with rheostat then source-series with low-voltage DC, Rheostatic slide plate is placed in resistance value close to maximum position, and closure switch move rheostatic slide plate, keep small bulbs brightness darker；
5th step disconnects switch, and observation disconnects moment small bulbs luminous situation, can be with multioperation several times；
6th step changes the coil in the 4th step circuit into tertiary coil, repeats the experimental implementation of the four, the 5th steps；
7th step changes the coil in the 4th step circuit into second coil, repeats the experimental implementation of the four, the 5th steps；
A kind of experimental method of electromagnetic induction experimental apparatus for researching, comprising the following steps:
One coil of the transformer connects low-voltage alternating current power supply, and small bulbs are connected with another coil of transformer, third line Circle is unloaded；
One coil of the first step, the transformer connects low-voltage alternating current power supply；
Second step, with A.C. voltmeter difference measuring transformer the first binding post and the second wiring intercolumniation, third binding post and 4th wiring intercolumniation, the 5th binding post and the 6th wiring intercolumniation input voltage or output voltage and record, analyze experimental data Whether the transformation ratio formula of ideal transformer is met；
Third step, a coil of the transformer connect low-voltage alternating current power supply, another coil string of the small bulbs and transformer Connection, third coil are unloaded；
4th step, with A.C. voltmeter difference measuring transformer the first binding post and the second wiring intercolumniation, third binding post and 4th wiring intercolumniation, the 5th binding post and the 6th wiring intercolumniation input voltage or output voltage and record；It probes into prompt: measuring After the input voltage of transformer, the big appointment of the voltage at predictable two secondary coil both ends of transformer once is how many, with exchange Voltmeter is attempted to explain experimental data after measuring the actual output voltages of two secondary coils.
A kind of experimental method of electromagnetic induction experimental apparatus for researching, comprising the following steps:
One coil of ammeter and transformer is connected into closed circuit, and it is (vertical in addition to prepare the stronger identical sheet of two magnetism The cylinders such as cube or cylinder, thickness are thinner) magnet；
One coil of the first step, small range ammeter and transformer is connected into closed circuit；
Second step, is layered on the upper surface (shielding) of transformer after taking Xiao Zhang's paper to fold, hand takes one piece of flaky magnet to exist The certain eminence of transformer overcentre (take one-pen cap to erect, magnet lower edge is equal with pen cap top when release every time, or Erected with objects such as graduated scales, discharge magnet from same position every time) static release, pays attention to allowing magnet surface holding level It falls on transformer, if it is not, please discharging again repeatedly.It observes the full-scale reading (deflection reading) of ammeter simultaneously and remembers Record；
Third step from the static release of transformer overcentre same position after two pieces of flaky magnets are stacked, while observing electric current The full-scale reading of ammeter compares in the full-scale reading of table, with second step experimental implementation；
Ammeter is changed to after being connected into closed circuit with another coil of transformer by the 4th step, and two pieces of flaky magnets are from transformation The static release of device overcentre same position, while the full-scale reading of ammeter is observed, with ammeter in third step experimental implementation Full-scale reading comparison；Or one piece of flaky magnet is from the static release of transformer overcentre same position, while observing electric current The full-scale reading comparison of ammeter in the full-scale reading of table, with second step experimental implementation.
A kind of experimental method of electromagnetic induction experimental apparatus for researching, comprising the following steps:
The first coil of transformer, switch, low-voltage dc power supply are connected into closed circuit；The first coil and third line of transformer It is source-series with low-voltage DC that circle passes through switch in the same direction or after reverse parallel connection；In addition prepare the sheet metal of 1 or more lightweight；
The first step, the first coil of transformer, switch, low-voltage dc power supply are connected into closed circuit；
Second step, face center areas adjacent puts the sheet metal of 1 or more lightweight on the transformer；
Third step, quick-make switch, observation sheet metal have He Fanying, then disconnect switch；
4th step connects the first binding post and the 5th binding post, the second binding post and the connection of the 6th binding post, and the of transformer One coil and tertiary coil pass through switch and low-voltage DC in the same direction (current direction for latter two coil that is powered is consistent) in parallel afterwards It is source-series；
5th step, closure switch, observation sheet metal have He Fanying, then disconnect switch；
6th step connects the first binding post and the 6th binding post, the second binding post and the connection of the 5th binding post, and the of transformer One coil and tertiary coil reverse parallel connection (current direction for latter two coil that is powered is opposite) pass through switch and low-voltage DC afterwards It is source-series；Switch is reclosed, observation sheet metal has He Fanying, then disconnects switch.
A kind of experimental method of electromagnetic induction experimental apparatus for researching, comprising the following steps:
In addition the enameled wire prepared puts in the gap of transformer, and one encloses on the iron core for being wound on transformer side, enamel-cover wire length Degree is proper between 1 meter to 2 meters, and a certain coil of transformer is source-series with low-voltage AC by switching；
The first step, is respectively scraped off the paint at enameled wire both ends with pocket knife a bit of, puts in the gap of transformer for one of enameled wire, One encloses on the iron core for being wound on transformer side, and completely around ten multi-turns (circle number is depending on enamel-cover line length), both ends are placed on On insulated platform.
The a certain coil of second step, transformer is source-series with low-voltage AC by switching, and powers on, uses alternating voltage Table successively measures the input voltage at this coil both ends of transformer and the output voltage at enameled wire both ends.
The technical program utilizes better simply device quantitative verification Faraday's electromagnetic induction law, can complete electromagnetic induction Relevant some experiments, work well, cost is also low；The present apparatus further solves the problems, such as physics experiments of high school, preferably cultivates The physics experiment ability of student.
Detailed description of the invention
Fig. 1 is structural schematic diagram of the invention；
Fig. 2 is the structural schematic diagram of embodiment 1；
Fig. 3 is the structural schematic diagram of embodiment 2；
Fig. 4 is the structural schematic diagram of embodiment 3；
Fig. 5 is the structural schematic diagram of embodiment 4；
Fig. 6 is the structural schematic diagram of embodiment 5；
Fig. 7 is the structural schematic diagram of embodiment 7；
In figure: rheostat (1), ammeter (2), small bulbs (3), transformer (4),
First coil (4a), the first binding post (401), the second binding post (402),
Second coil (4b), third binding post (403), the 4th binding post (404),
Tertiary coil (4c), the 5th binding post (405), the 6th binding post (406),
Low-tension supply (5), A.C. voltmeter (6), switch (7).
Specific embodiment
With reference to the accompanying drawing, the present invention is described in further details.
A kind of electromagnetic induction experimental apparatus for researching and its experimental method, including transformer (4), ammeter (2), small bulbs (3), Rheostat (1), low-tension supply (5), A.C. voltmeter (6), switch (7).
The transformer (4) includes that first coil (4a), the second coil (4b) and tertiary coil (4c), the number of turns are respectively n1、n2、n3, n1Greater than n3Greater than n2；The first binding post (401) and the second binding post is respectively set in first coil (4a) both ends (402)；Third binding post (403) and the 4th binding post (404) is respectively set in second coil (4b) both ends；The third line The 5th binding post (405) and the 6th binding post (406) is respectively set in circle both ends (4c)；The low-tension supply (5) is a kind of hands over directly Flow the combination of dual purpose low-voltage power supply or independent low-voltage alternating current power supply and independent low-voltage dc power supply.
The different resistive values of the first coil (4a), the second coil (4b) and tertiary coil (4c) are less big, do so When " quantitative verification Faraday's electromagnetic induction law ", one coil of selection and ammeter are connected into closed circuit every time, carry out pair Than experiment, it is believed that the all-in resistance of closed circuit is approximately equal in comparative experiments, so, the ratio between ammeter full-scale reading just reflects The ratio between maximum induced electromotive force.Three coil ratios setting flexibility is larger, preferably, the first coil The turn ratio of (4a), the second coil (4b) and tertiary coil (4c) are 4:1:2.
It should be strongly noted that first coil (4a), the second coil (4b) and tertiary coil (4c) be using function as It distinguishes, entity can be independent from each other, can also can also be merged with common part coil, two binding posts of corresponding position At one.
Total resistance value of the rheostat (1) is the Ω of 5 Ω ~ 200.Further, the rheostat (1) include slide rheostat or Person's potentiometer.
The ammeter (2) is small range ammeter, is milliammeter or microampere meter, several ohm of resistance value to several hundred Europe Nurse, preferably, the range of the ammeter (2) is 15mA.
The small bulbs (3) include bulb and the light bulb of 220V.Preferably, bulb specification be 6.3V, 0.15A or Person 2.5V, 0.3A, 3 watts of LED bulbs of the preferred 220V of the light bulb of 220V.
The A.C. voltmeter (6) can be digital multimeter or pointer universal metre.
As preferred: following 10 embodiments use the transformer (4) of same size, the first coil of transformer (4) The number of turns of (4a), the second coil (4b) and tertiary coil (4c) are respectively 4n, n, 2n, and the different resistive values of three coils are little.
Embodiment 1 quantitatively probes into Faraday's electromagnetic induction law (one)
Experiment purpose: Faraday's electromagnetic induction law is quantitatively probed into.
As preferred: 1 section dry cell of low-tension supply (5)；The specification of rheostat (1) is " 20 Ω, 2A "；Ammeter (2) Measurement range selection 15mA.
Experimental procedure: the first step, circuit diagram as shown in Figure 2 have connected circuit, the low-voltage dc power supply (5), switch (7), first coil (4a) series connection of rheostat (1), transformer (4) forms closed circuit；The slide plate of rheostat (1) is placed in resistance value Close to maximum position, the tertiary coil (4c) of transformer (4) connects to form closed circuit with ammeter (2).
Probe into prompt 1: the slide plate of rheostat (1) is first placed in resistance value close to maximum position, it is proposed that in the larger position of resistance value When closure switch (7) or disconnect switch (7).Preventing ammeter (2), deflection angle of indicator is excessive and damages ammeter.
Second step, closure switch (7), once fast moves the slide plate of rheostat (1), primary slowly mobile rheostat (1) Slide plate, the reading for comparing which primary current table (2) is larger.Then the slide plate of rheostat (1) is moved on into the larger position of resistance value, Disconnect switch (7).
Third step, closure switch (7), while observing the full-scale reading (deflection reading) of ammeter (2) and recording.
4th step disconnects switch (7), while observing the full-scale reading and record of ammeter (2).
The slide plate position of 5th step, rheostat (1) remains unchanged, by the second coil of ammeter (2) and transformer (4) (4b) forms series circuit, closure switch, while observing full-scale reading (deflection reading) and the third step experiment behaviour of ammeter (2) The full-scale reading of ammeter (2) compares in work.
6th step disconnects switch (7), while observing the full-scale reading of ammeter (2), with electric current in the 4th step experimental implementation The full-scale reading of table (2) compares.
7th step removes circuit, arranges equipment.
Probe into prompt 2: because the second coil (4b) with the resistance value of tertiary coil (4c) differs less big, respectively with ammeter (2) after forming series circuit, it is believed that the DC resistance of closed circuit is approximately equal in experimental implementation several times.
Experiment conclusion: in 1. second step experimental implementations, when fast moving the slide plate of rheostat (1), the reading of ammeter (2) Number is larger.Illustrate faster across the magnetic flux change of closed circuit, the induced electromotive force of generation is bigger.
2. third step and the 5th step experimental implementation compare, the DC resistance of closed circuit is approximately equal, passes through closure electricity The variation rate of magnetic flux on road is approximately equal, and the ratio between the number of turns of tertiary coil (4c) and the second coil (4b) is 2:1, ammeter (2) The former is approximately 2 times of the latter to full-scale reading, and the size for illustrating induced electromotive force is directly proportional to the number of turns of coil.
3. the 4th step and the 6th step experimental implementation compare, when switch disconnects, after the full-scale reading of the former ammeter is approximately 2 times of person, can similarly obtain, and the size of induced electromotive force and the number of turns of coil are directly proportional.
According to Faraday's electromagnetic induction law: the size of induced electromotive force in closed circuit, the magnetic with passing through this circuit The change rate of flux is directly proportional.If closed circuit is that a number of turns is using the International System of UnitsnCoil, faraday's electromagnetism The expression formula of induction law are as follows:.The above-mentioned experimental result quantitative testing correctness of Faraday's electromagnetic induction law.
The experimental method of the present embodiment, which can also slightly be made, to be changed, for example, the low-voltage dc power supply (5), switch (7), variable resistance The second coil (4b) series connection of device (1), transformer (4) forms closed circuit, the first third line with transformer (4) of ammeter (2) Circle (4c), which is connected, forms closed circuit, and the first coil (4a) of ammeter (2) and transformer (4) is formed series electrical in the 5th step Road；For another example, the low-voltage dc power supply (5), switch (7), rheostat (1), transformer (4) tertiary coil (4c) connect shape At closed circuit, ammeter (2) first connects to form closed circuit with the second coil (4b) of transformer (4), will be electric in the 5th step Flow table (2) and the first coil (4a) of transformer (4) form series circuit.
Embodiment 2 probes into inductor to the inhibition of alternating current
Experiment purpose: understanding inductor to the inhibition of alternating current, have a talk about self-induction of loop coefficient used in this experiment compared with It is big still smaller.
As preferred: low-tension supply (5) is AC and DC low-tension supply；The specification of small bulbs (3) is 6.3V, 0.15A； A.C. voltmeter (6) measurement range selection 20V.
Experimental procedure: the first step has connected circuit, the first coil (4a) and lampet of transformer (4) 4n circle by Fig. 3 circuit diagram Bubble (3), closure switch (7) series connection are followed by low-tension supply (5), and low-tension supply (5) selects direct current 6V gear.
Second step, closure switch (7) observe small bulbs (3) luminous situation.
Third step disconnects switch, and low-tension supply (5) changes exchange 6V gear into, re-closes switch, observation small bulbs (3) hair Light situation.
It probes into prompt 1: when changing exchange 6V power supply into, noticing that observing small bulbs (3) is that brightness change is a little, still completely not It is bright.
4th step, A.C. voltmeter (6) measurement range selection exchange 20V gear.By the wiring at two test pencils contact small bulbs (3) both ends Column observes the registration of A.C. voltmeter (6).
Coil is changed into the tertiary coil (4c) of 2n circle, repeats step 1 to four by the 5th step.
6th step changes coil into the second coil of n circle (4b), repeats step 1 to four.
7th step pulls out plug, removes circuit, arranges equipment.
Probe into prompt 2: the choke coil in electrotechnics and electronic technique is divided to two classes, and one kind is low-frequency choke coil, and coil is wound on iron On core, there are many number of turns, big to the inhibition of exchange, and characteristic is summarised as " logical direct current, resistance exchange "；Another kind of is high frequency choke Circle, coil are wound on ferrite core or hollow, and the number of turns is few, and electrodynamic capacity is small, and characteristic is summarised as that " logical direct current, logical low frequency, resistance are high Frequently ".Sort out according only to the characteristic that coil shows in an experiment, you think which kind of the coil in transformer can be grouped into respectively Choke coil.
Experimental phenomena: certain experiment in, second step operation in, with coil (4a) concatenated small bulbs (3) light emission luminance compared with It is high.In third step, do not shine with coil (4a) concatenated small bulbs (3).A.C. voltmeter registration is close to zero in 4th step.The In five steps, small bulbs (3) filament is rubescent, does not see luminous, and voltmeter registration is 0.79V or so.In 6th step, small bulbs (3) It shines, but brightness is darker, measuring both end voltage is 3.32V or so.
Experiment conclusion: above-mentioned experimental phenomena illustrates that inductance coil has inhibition to alternating current.According in transformer (4) The characteristic that three coils show in an experiment.First coil (4a) the number of turns of 4n circle is most, and line footpath is also thick, electrodynamic capacity It is larger, play the role of " logical direct current, resistance exchange " in this experiment, it is believed that be a low-frequency choke coil.Second coil of n circle (4b) the number of turns is minimum, and line footpath is also thin, and electrodynamic capacity is smaller, and Low-frequency alternating currents can be allowed by coil, but also has obstruction to make With (light bulb A brightness is darker), it is believed that be a high frequency choke coil.The characteristic that the tertiary coil (4c) of 2n circle shows between Between the two.
3 self-inductance power phenomenon of embodiment is probed into: small bulbs are glittering once
Experiment purpose: understanding and explains self-inductance power phenomenon, while recognizing the electrodynamic capacity of coil and the size of coil, shape Shape, circle number etc. are related.
As preferred: low-tension supply (5) is that 2 section dry cells are connected the battery pack to be formed；The specification of small bulbs (3) is 3 watts of LED bulbs of 6.3V, 0.15A(or 220V).
Experimental procedure: the first step, by small bulbs (3) it is in parallel with first coil (4a) of transformer (4) after with low-tension supply (5) it connects, circuit diagram as shown in Figure 4 connects circuit.
Second step, closure switch observe the brightness of small bulbs (3).
Third step, disconnects switch, and observation disconnects moment small bulbs (3) luminous situation.
Coil is changed into the tertiary coil (4c) of transformer (4) by the 4th step, repeats to test.
Coil is changed into the second coil (4b) of transformer (4) by the 5th step, repeats to test.
6th step removes circuit, arranges equipment.
Safety instruction: transformer (4) coil conduction time is not too long, in order to avoid damage transformer (4).
It probes into prompt: please explain experimental phenomena, and be thought deeply according to knowledge, to disconnect moment, observation in switch (7) Once extinguish again to small bulbs (3) are glittering, has what requirement to the resistance value of two branches.
Experimental phenomena: in third step operation, switch (7) disconnects moment, it is seen that small bulbs (3) are glittering once to be extinguished again, existing As very clear.In FOUR EASY STEPS, switch (7) disconnects moment, and small bulbs (3) are slightly bright a little to be extinguished again.5th step behaviour In work, switch (7) disconnects moment, does not see that small bulbs (3) are glittering and once extinguishes again, also extinguishes effect without obvious delay.
Experiment conclusion: 1. switches (7) disconnect moment, and coil generates the reduction that self induction electromotive force hinders electric current, and coil plays Power supply effect, the current value in small bulbs (3) is gradually reduced since the normal current value of coil at this time, but to see small bulbs (3) brighter once to extinguish again, it is necessary to make to switch more much bigger (i.e. than the electric current of small bulbs (3) by the electric current of coil before (7) disconnect The resistance value of coil is more much smaller than the resistance value of small bulbs (3)).
In the operation of fourth, fifth step, the glittering effect once of small bulbs (3) is unobvious, tests three times, before switch (7) disconnects, three The different resistive values of a coil are little, then are not much different by the current value of coil, and after switch (7) disconnects, circuit all-in resistance is poor Not less, the electrodynamic capacity for being primarily due to three coils is different (self-induction action is strong and weak different), coil is thicker, the number of turns is more, In addition iron core, electrodynamic capacity is bigger.The multi-thread diameter of first coil (4a) the number of turns of 4n circle is thick, and electrodynamic capacity is big, and experiment effect is good. And to lack line footpath thin for the second coil (4b) the number of turns of n circle, electrodynamic capacity is minimum, and experiment effect is also worst.
Embodiment 4 probes into the factor for influencing self-inductance power effect
Experiment purpose: understanding and explains self-inductance power phenomenon, at the same probe into influence experiment effect because which is known as.
As preferred: low-tension supply (5) is that 2 section dry cells are connected the battery pack to be formed；The specification of rheostat (1) is 20 Ω,2A；The specification of small bulbs (3) is 2.5V, 0.3A.
Experimental procedure: the first step, by small bulbs (3) it is in parallel with first coil (4a) of transformer (4) after with low-voltage direct Power supply (5) series connection.
Second step, closure switch (7) observe the brightness of small bulbs (3).
Third step, disconnects switch (7), and observation disconnects moment small bulbs (3) luminous situation.
4th step, small bulbs (3) are connected with rheostat (1), have connected circuit, the cunning of rheostat (1) by the circuit diagram of Fig. 5 Piece is placed in resistance value close to maximum position.Closure switch (7), the slide plate of mobile rheostat (1), keep small bulbs (3) brightness darker.
5th step, disconnects switch (7), and observation disconnects moment small bulbs (3) luminous situation.Switch is re-closed, then is disconnected It switchs (7), can observe several times more.
Coil is changed into the tertiary coil (4c) of 2n circle by the 6th step, repeats the experimental implementation of the four, the 5th steps.
Coil is changed into the second coil (4b) of n circle by the 7th step, repeats the experimental implementation of the four, the 5th steps.
8th step removes circuit, arranges equipment.
Safety instruction: transformer (4) coil conduction time is not too long, in order to avoid damage transformer (4).
It probes into prompt: please explain experimental phenomena, and be compared and analyzed with the experiment effect of last experiment.
Experimental phenomena: during third step, the 6th step, the 7th step operate, switch-off instant does not obviously observe small bulbs It is brighter once to extinguish again.In the operation of 5th step, switch-off instant, it can be seen that small bulbs are brighter once to be extinguished again.
Experiment conclusion: 1. small bulbs (3) are connected with rheostat (1), when keeping small bulbs (3) brightness darker, the resistance of coil Value is much smaller than total resistance value of small bulbs (3) and rheostat (1), and switch disconnects the preceding electric current by coil and is much larger than small bulbs (3) Electric current.In this way, the electric current in small bulbs (3) is gradually reduced since the normal current value of coil, longer when switch disconnects Current value is still greater than lamp current value when closing the switch in time, so in the operation of the 5th step, it can be seen that small bulbs (3) are more It is bright once to extinguish again.It is seldom small although coil resistance is less than lamp resistance but in third step operation, therefore switch disconnected Electric current before opening by coil is not much larger than the electric current of small bulbs (3), and small bulbs (3) brighter effect once is not when switch disconnects Obviously.Therefore the brighter first once condition of small bulbs (3) is: switch passes through the electric current of coil than small bulbs (3) before disconnecting Electric current it is much bigger.
In 6th step, the operation of the 7th step, although meeting first condition, small bulbs (3) luminous effect is unobvious, main If because the electrodynamic capacity of three coils is different.The electrodynamic capacity of 4n circle thick line circle is big, and experiment effect is good.And the filament of n circle Circle, electrodynamic capacity is minimum, and experiment effect is also worst.Therefore the brighter second once condition of small bulbs is: the self-induction system of coil Number wants sufficiently large.
It is compared with embodiment 3, when closing the switch, two lamp brightness are darker, and electric current is respectively less than respective rated current Value.But the rated current of 2.5V small bulbs (3) is 0.3A, and 6.3V small bulbs (3) although voltage rating is high, only have by rated current 0.15A.Switch-off instant, the current value in small bulbs is all to be gradually reduced since the normal current value of coil, but pass through The time that the electric current of 6.3V small bulbs (3) is maintained at load current value or more is longer, so the glittering effect once of 6.3V small bulbs Fruit is more preferable.
The voltage at transformer coil both ends is probed under the power supply situation of embodiment 5
Experiment purpose: by probing into, being further recognized by transformation ratio formula and be only applicable in ideal transformer, since loss is made when power supply It is reduced at transformer secondary coil virtual voltage.
As preferred: low-tension supply (5) is low-voltage alternating current power supply；The specification of small bulbs (3) is 6.3V, 0.15A；Alternating current Press table (6) measurement range selection 20V.
One coil of the transformer (4) connects low-tension supply (5)；The residue one of the small bulbs (3) and transformer (4) Coil series connection；With the first binding post (401) and the second binding post (402) of A.C. voltmeter (6) difference measuring transformer (4) Between, it is defeated between third binding post (403) and the 4th binding post (404), between the 5th binding post (405) and the 6th binding post (406) Enter voltage or output voltage；The low-tension supply (5) is low-voltage alternating current power supply.Experimental procedure: the first step, with conducting wire by transformer (4) tertiary coil (4c) of 2n circle connects AC and DC low-tension supply (5) (selection exchange 4V gear).
Second step powers on, and is connect with the 5th binding post (405) of A.C. voltmeter (6) measuring transformer (4), the 6th Input voltage between terminal (406), output voltage and third wiring between the first binding post (401), the second binding post (402) Whether output voltage and record between column (403), the 4th binding post (404), analysis experimental data meet the change of ideal transformer Pressure ratio formula。
Third step disconnects power supply, connects circuit by the circuit diagram of Fig. 6, i.e. it is low that the tertiary coil (4c) of 2n circle connects exchange The first coil (4a) of voltage source (5), 4n circle powers to small bulbs (3), and the second coil (4b) of n circle is unloaded.
4th step, powers on, and first observes small bulbs (3) luminous situation.A.C. voltmeter (6) measuring transformer is used again (4) input voltage between the 5th binding post (405), the 6th binding post (406), the first binding post (401), the second binding post (402) output voltage (i.e. the voltages at small bulbs (3) both ends) between, between third binding post (403), the 4th binding post (404) Output voltage simultaneously records.
It probes into prompt 1: after the input voltage for measuring transformer (4), two secondary coil both ends of transformer can be predicted The big appointment of voltage be how many, measured with A.C. voltmeter (6) and attempt after the actual output voltage of two secondary coils to explain reality Test data.
5th step disconnects switch, pulls out plug, removes circuit, arranges equipment.
Experimental data: in certain experiment, when no-load transformer (not connecing small bulbs), the 5th binding post (405), the 6th are measured Input voltage between binding post (406) is 4.69V, and the output voltage between the first binding post (401), the second binding post (402) is 9.27V, the output voltage between third binding post (403), the 4th binding post (404) are 2.31V.Transformer (4) is to small bulbs (3) After power supply, the input voltage of transformer (4) is reduced to 4.48V, and the first binding post (401), the second binding post (connect lampet between (402) Bubble (3)) output voltage be reduced to 6.85V, the output voltage between third binding post (403), the 4th binding post (404) is reduced to 1.78V。
Experiment conclusion: when no-load transformer (not connecing small bulbs), the first binding post (401) of transformer (4), the second wiring Output voltage between column (402) is 2 times of input voltage, the output electricity between third binding post (403), the 4th binding post (404) Pressure is 0.5 times of input voltage, all meets fairly good with the transformation ratio formula of ideal transformer.Transformer (4) is to small bulbs (3) after powering, output and input voltage does not reduce in proportion.Two the second coils of secondary coil (4b) and tertiary coil (4c) Output voltage all compare formulaPredicted value it is one section low.Because the former and deputy coil of the transformer has resistance, wherein Heating loss's (copper loss) that electric current in two coils generates is larger, iron loss also than zero load when it is big, not only connect the secondary coil of light bulb Both end voltage is lower than formula predictions value, another unloaded secondary coil (between third binding post (403), the 4th binding post (404)) Both end voltage can also be lower than formula predictions value.
The present embodiment is using boosting power supply circuit, naturally it is also possible to be tested using step-down power supply circuit.Such as: The first coil (4a) of transformer (4) connects low-voltage alternating current power supply (5)；The tertiary coil (4c) of 2n circle is to the small of 2.5V, 0.3A The second coil (4b) of light bulb (3) power supply, n circle is unloaded.With the first binding post of A.C. voltmeter (6) measuring transformer (4) (401), the input voltage between the second binding post (402), the output electricity between the 5th binding post (405), the 6th binding post (406) Pressure, the output voltage between third binding post (403), the 4th binding post (404).
Embodiment 6 quantitatively probes into Faraday's electromagnetic induction law (two)
Experiment purpose: Faraday's electromagnetic induction law is quantitatively probed into.
As preferred: the range of ammeter (2) is 15mA, provide for oneself the stronger identical sheet of two magnetism (cube or The cylinders such as cylinder, thickness are thinner) magnet.
Experimental procedure: the first coil (4a) of the first step, ammeter (2) and transformer (4) 4n circle is connected into closed circuit, Ammeter (2) measurement range selection 15mA gear.
Second step holds 2 pieces of flaky magnets, close transformer (4) from transformer (4) top, primary quickly close, once It is slowly close, compare the size of ammeter pointer drift angle twice.
Third step, is layered on the upper surface (shielding) of transformer (4) after taking Xiao Zhang's paper to fold, hand takes a block piece shape Magnet (takes one-pen cap to erect, every time magnet lower edge and pen cap top when release in the certain eminence of transformer (4) overcentre Hold equal, or erected with objects such as graduated scales, discharge magnet from same position every time) static release, pay attention to allowing magnet table Face holding level is fallen on transformer (4), if it is not, please discharging again repeatedly.The full-scale reading of ammeter (2) is observed simultaneously (deflection reading) simultaneously records.
4th step is seen simultaneously from the static release of transformer (4) overcentre same position after two pieces of flaky magnets are stacked The full-scale reading for examining ammeter (2), withThe full-scale reading of ammeter (2) compares in step experimental implementation.
Probe into prompt 1: because the all-in resistance of closed circuit is constant, the ratio between full-scale reading of ammeter reflects induction electric The ratio between gesture size.In addition, magnet is discharged from transformer overcentre same position, illustrate that experiment magnet is close to transformer twice Speed be it is equal, can be approximately considered, variation rate of magnetic flux when two blocks of magnet fall across closed circuit is under one block of magnet Twice of variation rate of magnetic flux when falling.
Ammeter (2) is changed to be connected into closed circuit with the tertiary coil (4c) of the 2n circle of transformer (4) by the 5th step, Two pieces of flaky magnets observe the full-scale reading of ammeter (2) from the static release of transformer (4) overcentre same position, It is compared with the full-scale reading of ammeter in the 4th step experimental implementation.
6th step removes circuit, arranges equipment.
Probe into prompt 2: because the resistance value of two coils is not much different, after forming series circuit with ammeter, it is believed that The DC resistance of closed circuit is approximately equal in experimental implementation twice.
Experimental data: in step 3, when one block of magnet falls, ammeter maximum deflectionLattice.
In step 4, when two blocks of magnet fall, ammeter maximum deflectionLattice.
In step 5, when two blocks of magnet fall, ammeter maximum deflectionLattice.
Experiment conclusion: when 1. " quickly close ", the magnetic flux change across closed circuit is very fast, ammeter pointer it is inclined Corner is larger, illustrates that the induced current in circuit at this time is larger.As it can be seen that the magnetic flux change for passing through closed circuit is faster, generate Induced electromotive force it is bigger.
The full-scale reading of ammeter is approximately two of ammeter full-scale reading when one block of magnet falls when two blocks of magnet fall Times.Illustrate that the size of induced electromotive force is directly proportional to the variation rate of magnetic flux of closed circuit is passed through.
4th step and the 5th step experimental implementation compare, and the DC resistance of closed circuit is of substantially equal, pass through closed circuit Variation rate of magnetic flux it is approximately equal, the ratio between coil turn is 2:1, the former is approximately 2 times of the latter for the full-scale reading of ammeter, It is believed that the size of induced electromotive force is directly proportional to the number of turns of coil.Summary can obtain Faraday's electromagnetic induction law: closed circuit The size of middle induced electromotive force, it is directly proportional with passing through the change rate of magnetic flux of this circuit.If closed using the International System of Units Closing circuit is that a number of turns isnCoil, the expression formula of Faraday's electromagnetic induction law are as follows:.
The energization moment mutual inductance phenomenon of embodiment 7 is probed into: skip ring experiment
Experiment purpose: understanding " jumps ring phenomenon ", and the physical principles such as trial Lenz's law explain " jumping ring phenomenon ".
As preferred: low-tension supply (5) is that 2 section dry cells are connected the battery pack to be formed；Light-weight metal piece 4.
Experimental procedure: the first step, the first coil (4a) of transformer (4), switch, low-voltage dc power supply (5) are connected into and close Close circuit.
Second step respectively puts the sheet metal of 1 lightweight near four angles of transformer (4) upper surface nameplate (in nameplate) (primary screw gasket that can be less flat with surface).
Third step, quick-make switch, observation sheet metal have He Fanying, then disconnect switch.
4th step, circuit, the first binding post (401) and the 5th binding post (405) is connected, the second wiring as shown in Figure 7 Column (402) and the connection of the 6th binding post (406), the first coil (4a) and tertiary coil (4c) of transformer (4) are in parallel in the same direction (logical The current direction of latter two electric coil is consistent) it is connected afterwards by switching (7) with low-voltage dc power supply (5).
5th step, closure switch (7), observation sheet metal have He Fanying, then disconnect switch.
6th step, the first binding post (401) and the 6th binding post (406) are connected, and the second binding post (402) and the 5th connects Terminal (405) connection, (be powered latter two coil for the first coil (4a) and tertiary coil (4c) reverse parallel connection of transformer (4) Current direction is opposite) it is connected afterwards by switching (7) with low-voltage dc power supply (5).Experiment is repeated, the reaction of sheet metal is observed, Then disconnect switch.
7th step removes circuit, arranges equipment, attempts to explain experimental phenomena.
Experimental phenomena: in third step and the operation of the 5th step, moment is closed the switch, some sheet metals have been jumped (if not jumping It rises or shakes, battery please be renew).In the operation of 6th step, moment is closed the switch, no sheet metal takeoffs.
Experiment conclusion: after 1. close the switch, the coil in transformer has electric current by (being equivalent to energization solenoid), just Magnetic field can be generated in surrounding space.Moment is being closed the switch, the magnetic flux across sheet metal increases suddenly, just produces in sheet metal Induced current is given birth to.According to Lenz's law, effect caused by induced current will always hinder to cause faradic magnetic flux Variation, sheet metal have the tendency that reducing direction towards magnetic flux moves, i.e., the Ampere force that induced current is subject in sheet metal is upward, because It is very light for the sheet metal in experiment, its gravity is greater than by upward Ampere force, so it is observed that sheet metal is jumped upwards It rises, referred to as skip ring experiment.
In the operation of 6th step, moment is closed the switch, although thering is electric current to pass through in two coils, because in two coils Current direction be it is opposite, the magnetic field of generation can be offset, across sheet metal magnetic flux increase degree be not so good as preceding secondary experiment, sense Answer electric current not big enough, sheet metal can not jumped.
The voltage at transformer coil both ends is probed under 8 leakage field situation of embodiment
Experiment purpose: it by probing into, is further recognized by transformation ratio formula and is only applicable in ideal transformer, biggish transformer is lost Secondary coil virtual voltage is significantly lower than theoretical value.
As preferred: low-tension supply (5) is low-voltage alternating current power supply；A.C. voltmeter (6) available digital multimeter, range choosing Select 20V.Provide enameled wire for oneself, length is proper between 1 meter to 2 meters, 1.4 meters of the enamel-cover line length in experiment.
Experimental procedure: the first step, the paint at 1.4 meters long of enameled wire both ends respectively scraped off with pocket knife it is a bit of, by enameled wire A gap for putting in transformer (4), one encloses on the iron core for being wound on transformer (4) side, around complete 15 circle (circle number Depending on enamel-cover line length), both ends are put on the table.
Second step, the first coil (4a) of transformer (4) are connected by switching (7) with low-voltage alternating current power supply (5), and selection is handed over Galvanic electricity presses 6V output gear, powers on, successively measures both ends first coil (4a) of transformer (4) with A.C. voltmeter (6) The output voltage of input voltage and enameled wire both ends.
Probe into prompt 1: if digital multimeter has a test pencil and enamel-cover the end of a thread poor contact (may paint and not scrape completely), The voltage value of display can improve one section (also higher than the theoretical expectation values of ideal situation) instead.Therefore, when operation, test pencil please be change Surveyed with the contact position of enamel-cover the end of a thread several times more, etc. read after stable readings again.And a test pencil is taken away consciously, it observes more With the variation for indicating number.
Third step, disconnects power supply, and low-voltage alternating current power supply (5) changes alternating voltage 4V output gear into, re-measures primary.
4th step disconnects switch (7), pulls out plug, arranges equipment.
Probe into prompt 2: the shape of transformer (4) iron core be "", three groups of coils (4n, 2n, n circle) of transformer are all It is wound in this intermediate arm.In this experiment, 4n circle coil connects AC power source, is primary coil, 15 circles of winding by hand around aside this It is secondary coil in arm.Obviously, the magnetic flux across primary coil (intermediate iron core) is big, and the magnetic flux across secondary coil is small, magnetic flux Amount has leakage.First coil (4a) the number of turns (i.e. 4n) of known transformer is greater than some value of 150 circles, asks you according to transformer Structure and Binding experiment data, infer first coil (4a) the number of turns the upper limit.
Experimental data: stepIn measure input voltage and beV, output voltage areV；StepIn measure Input voltage isV, output voltage areV.Twice in measurementU 1/U 2Average value be。
Experiment conclusion: if iron core is the ideal transformer of " mouth " shape, according to transformation ratio formula, because of n2= 15 circles acquire primary coil the number of turns n1=, still, practical upper core is shape, even if passing through former line without other losses The magnetic flux of circle also only has half to have half to miss (not utilizing) by secondary coil, that is, magnetic flux, according to faraday's electricity Law of magnetic induction, the induced electromotive force that secondary coil generates can halve, and also halve when calculating primary coil the number of turns in this way, finally n1 is real= n1/2=, it is contemplated that the miniature transformer in experiment is necessarily lossy, therefore first coil (4a) the number of turns n1 is realIt must So it is less than n1/2。
Illustrate: in the present embodiment, the second coil (4b) or tertiary coil (4c) that transformer (4) also can be selected are by opening Close (7) and low-voltage alternating current power supply (5) concatenated experimental program.
The boosting power supply test experiments of embodiment 9
Experiment purpose: it attempts to boost using transformer for electrical testing, it is known that miniature transformer is not ideal.
Low-tension supply (5) is low-voltage alternating current power supply, preferably, the specification of small bulbs (3) is 6.3V, 0.15A；Alternating current Press table (6) measurement range selection 20V.
Experimental procedure: the tertiary coil (4c) of the first step, the 2n circle of transformer (4) connects low-voltage AC/DC double-purpose electric source (5), the first coil (4a) of output voltage selection exchange 4V gear, 4n circle powers to the small bulbs (3) that specification is 6.3V, 0.15A, The second coil (4b) of n circle is unloaded.
Attaching plug is inserted into socket (voltage 220V), powered on, observes small bulbs (3) luminous situation by second step.
Probe into prompt: transformer (4) input termination is exchange 4V gear, actual measurement input voltage 4.5V or so, former and deputy coil Turn ratio is 1:2, notices that the small bulbs for observing voltage rating 6.3V can no damage.
Third step, input voltage and output voltage (i.e. small bulbs both ends with digital multimeter (6) measuring transformer (4) Voltage), measurement range selection exchange 20V gear.
4th step is attempted to explain experimental phenomena, pulls out plug, and digital multimeter (6) switch pushes OFF position, removes electricity Road arranges equipment.
Experimental data: in certain experiment, small bulbs (3) normal luminous when power supply, measuring transformer (4) input voltage is 4.52 V, measuring secondary coil output voltage is 6.97 V.
Experiment conclusion: the former and deputy coil in transformer is to be wound on skeleton, and mutually insulated, its working principle are electricity Mutual inductance principle in magnetic induction.Experimental data explanation, output voltage when transformer connects small bulbs are lower than ideal transformer transformation Than the predicted value of formula.This is because transformer is not preferably, former and deputy coil has biggish resistance, when electric current passes through coil Heating loss's (copper loss) of generation is larger, iron loss also than zero load when it is big, output voltage just reduces.And coil current is when unloaded Zero, copper loss is negligible.
The decompression power supply test experiments of embodiment 10
Experiment purpose: understand transformer pressure-reducing power supply the principle.It is ideal for knowing miniature transformer not.
Low-tension supply (5) is low-voltage alternating current power supply, preferably, the specification of small bulbs (3) is 2.5V/0.3A；Alternating current Press table (6) measurement range selection 20V.
Experimental procedure: the first coil (4a) of the first step, transformer 4n circle connects low-voltage AC/DC double-purpose electric source (5), selection Exchange output 6V gear, tertiary coil (4c) coil of 2n circle power to the small bulbs (3) that specification is 2.5V/0.3A.
Attaching plug is inserted into socket (voltage 220V), powered on, observes small bulbs (3) luminous situation by second step.
Third step, input voltage and output voltage (i.e. small bulbs both ends with digital multimeter (6) measuring transformer (4) Voltage), measurement range selection exchange 20V gear.
4th step pulls out plug, and multimeter switch pushes OFF position, removes circuit, arranges equipment.
Experimental phenomena: small bulbs (3) normal luminous when power supply, but output voltage when transformer (4) connects small bulbs is lower than The predicted value of transformation ratio formula.
Experiment conclusion: the former and deputy coil ratio of transformer is 2:1, according to the transformation ratio formula of ideal transformer, by-pass Enclose the half that both end voltage is input voltage.In certain experiment, when transformer powers to small bulbs, measuring input voltage is 6.87 V, secondary coil output voltage only have 2.44V, the reason is that this transformer be not it is ideal, coil has a resistance value, copper loss when power supply, Iron loss is larger, and output voltage is more much lower than formula predictions value.
The technical program have it is below the utility model has the advantages that
1. Faraday's electromagnetic induction law is an important law of high school physics, although existing scholar proposes experimental technique side Case, but it is at high cost, it operates relative complex.In high school physics field research, it is limited to the condition of laboratory of middle school, is difficult to be determined Amount verifying, teacher can only directly introduce Faraday's electromagnetic induction law in conjunction with History of Physics, be unfavorable for the understanding and grasp of student. The technical program utilizes better simply device quantitative verification Faraday's electromagnetic induction law, works well, also low (and the device of cost Material is shared with much experiments).
2. the experiment of self-inductance power phenomenon is the lecture experiment that Middle School Physics classroom must be done, with 2446 type self inductances of school Demonstration device does the experiment of self-inductance power phenomenon, although it is observed that bulb is glittering once extinguishes, but many students can be caused Misunderstanding, it is believed that the self induction electromotive force that coil generates do not exceed original supply voltage (because of supply voltage 4V, small electric light volume Constant voltage is also 4V), meanwhile, school's scheme (only one big coil) can not also probe into the factor for influencing experiment effect.This hair Power supply is 3V(2 section dry cell in bright technical solution), in embodiment 2, small bulbs specification is 6.3V, 0.15A, is closed the switch When, small bulbs glimmer, switch-off instant, 6.3V small bulbs are brighter suddenly once to be extinguished.When making student to down circuitry, cause Coil generate induced electromotive force it is more much higher than supply voltage, the fact that more convince.In experimental example 3, small bulbs specification It is changed to 2.5V, 0.3A, adds rheostat in circuit, in two embodiments, three coils of transformer are all respectively in an experiment It is tested, is recognized in the analysis relatively for allowing student to pass through experimental phenomena, the brighter first once condition of small bulbs is: Switch is more much bigger than the electric current of small bulbs by the electric current of coil before disconnecting；Second condition is: the electrodynamic capacity of coil is wanted It is sufficiently large.And it also is appreciated that the electrodynamic capacity of coil is related with the thickness of coil and the number of turns, coil is thicker, the number of turns is more, adds Upper core, electrodynamic capacity are bigger.These effects are all that the existing experimental program of school is unable to reach.
3. the existing experimental program of school can only simply demonstrate a coil (inductor) to the inhibition of alternating current.This What the embodiment 2 of scheme of the invention was done is also this experiment, because the line footpath and the number of turns of three coils are designed just to arrive in transformer Benefit, three coils are larger to the inhibition difference of alternating current in an experiment, represent three kinds of typical cases just, reach More perfect experiment effect.First coil (4a) line footpath of 4n circle is thick, and electrodynamic capacity is larger, plays in this experiment " logical The effect of direct current, resistance exchange ", it is believed that be a low-frequency choke coil.The second coil (4b) line footpath of n circle is thin, electrodynamic capacity compared with It is small, Low-frequency alternating currents can be allowed by coil, but also have inhibition, it is believed that be a high frequency choke coil.The of 2n circle The characteristic that three-winding (4c) shows falls between.
4. " probing into the voltage at transformer coil both ends and the relationship of the number of turns " experiment is classroom inquiry experiment by teaching material arrangement And student experimenting.The student experimenting that this needs everybody to start performs practically no function in most schools, and main cause is to use school The experimental result that equipment (transformer) obtains differs too big with theoretical expectation values.Because of refectory " removable transformation of imparting knowledge to students Device ", loss (leakage field and iron core vortex etc.) is also larger when unloaded, 80% of the voltage value that secondary coil measures less than theoretical expectation values (result is 75% or so).And when doing this experiment with the transformer in the present invention, the voltage value that secondary coil measures when unloaded reaches reason By 99% or more of predicted value.In this way, summarizing, to obtain the transformation ratio formula of ideal transformer be the thing that when the water comes, a channel is formed, with a high credibility. In the embodiment 5 of the present invention program, and probe under situation of powering the voltage at transformer coil both ends.It is supplied by measurement discovery Under electric situation, the output voltage of two secondary coils of transformer all compares formulaPredicted value it is one section low.Student is allowed to exist The difference that practical miniature transformer and ideal transformer are recognized during explaining phenomenon, improves the energy of solving practical problems Power.
5. the achievable electromagnetic induction of the technical program relevant 20 or more experiments (slightly increasing point equipment), including probe into Faradic Production conditions (magnet is close to coil) probe into faradic Production conditions (imitating Faraday's experiment), visit Study carefully the method (Lenz's law) of inductive current direction that determines, quantitatively probe into Faraday's electromagnetic induction law (one), quantitative inquiry method The law of electromagnetic induction (two), self-inductance power phenomenon is drawn to probe into (headlamp that a section dry cell lights 220V), self-inductance power existing As probing into (experiment is hit in safety body electrical verification), self-inductance power phenomenon probe into (small bulbs experimental program), probe into influence self-inductance power effect The factor of fruit, the moment self inductance that is powered inquiry experiment, to probe into inductor existing to the inhibition of alternating current, power-off mutual inductance As probing into (headlamp that a section dry cell lights 220V), power-off mutual inductance phenomenon probes into (experiment is hit in safety body electrical verification), is powered wink Between mutual inductance phenomenon probe into (skip ring experiment), probe into the voltage at transformer coil both ends and the relationship of the number of turns (quantitatively probes into faraday The law of electromagnetic induction three), boosting power supply test experiments, decompression power supply test experiments, probe into can not when transformer connects DC power supply It can transmit and probe into transformer coil both ends under the voltage for probing into transformer coil both ends under electric energy, power supply situation, leakage field situation Voltage etc., works well, and cost is also low.The technical program further solves the problems, such as physics experiments of high school, preferably training student Physics experiment ability.
The present invention is illustrated according to embodiment, under the premise of not departing from present principles, if the present apparatus can also make Dry modification and improvement.It should be pointed out that it is all using modes technical solutions obtained such as equivalent substitution or equivalent transformations, all fall within this In the protection scope of invention.

Claims (10)

1. a kind of electromagnetic induction experimental apparatus for researching and its experimental method, which is characterized in that including transformer (4), ammeter (2), Small bulbs (3), rheostat (1), low-tension supply (5), A.C. voltmeter (6), switch (7)；The transformer (4) includes First Line Enclosing (4a), the second coil (4b) and tertiary coil (4c), the number of turns is respectively n1、n2、n3, n1Greater than n3Greater than n2；The First Line The first binding post (401) and the second binding post (402) is respectively set in circle both ends (4a)；Second coil (4b) both ends are set respectively Set third binding post (403) and the 4th binding post (404)；The 5th binding post is respectively set in tertiary coil (4c) both ends (405) and the 6th binding post (406)；The low-tension supply (5) is a kind of AC and DC low-tension supply or independent low pressure The combination of AC power source and independent low-voltage dc power supply；
A coil in the low-tension supply (5), switch (7), rheostat (1) and transformer (4) connects to form closed circuit, institute It states ammeter (2) to connect to form another closed circuit with one coil of residue of transformer (4), the low-tension supply (5) is low pressure DC power supply；
The first coil (4a) or the second coil (4b) or tertiary coil (4c) of the transformer (4), with small bulbs (3), switch (7), low-tension supply (5) series connection forms closed circuit；
After the small bulbs (3) are in parallel with the first coil (4a) of transformer (4) or the second coil (4b) or tertiary coil (4c) It connects with low-tension supply (5), the low-tension supply (5) is low-voltage dc power supply；
The small bulbs (3) connect with rheostat (1) after with the first coil (4a) or the second coil (4b) of transformer (4) or Three-winding (4c) is in parallel, then connects with low-tension supply (5), and the low-tension supply (5) is low-voltage dc power supply.
2. a kind of electromagnetic induction experimental apparatus for researching as described in claim 1, which is characterized in that the first coil (4a), the The different resistive values of two coil (4b) and tertiary coil (4c) are less big, and one of coil and ammeter (2) is selected to go here and there every time When being unified into closed circuit, the all-in resistance of three closed circuits is approximately equal, and difference is no more than 20%.
3. a kind of experimental method of electromagnetic induction experimental apparatus for researching as claimed in claim 2, which is characterized in that including following step It is rapid:
A coil in the low-tension supply (5), switch (7), rheostat (1) and transformer (4) connects to form closed circuit, institute It states ammeter (2) to connect to form another closed circuit with one coil of residue of transformer (4), the low-tension supply (5) is low pressure DC power supply；
The first step, first coil (4a) series connection of the low-voltage dc power supply (5), switch (7), rheostat (1), transformer (4) Form closed circuit；The slide plate of rheostat (1) is placed in the larger position of resistance value, the tertiary coil (4c) and ammeter of transformer (4) (2) series connection forms closed circuit；
Second step, closure switch (7), while observing the full-scale reading (deflection reading) of ammeter (2) and recording；
Third step disconnects switch (7), while observing the full-scale reading and record of ammeter (2)；
The slide plate position of 4th step, rheostat (1) remains unchanged, by the second coil (4b) group of ammeter (2) and transformer (4) At series circuit, closure switch (7), while the full-scale reading for observing ammeter (2) and ammeter (2) in second step experimental implementation Full-scale reading compare；
5th step disconnects switch (7), while observing the full-scale reading of ammeter (2), with ammeter in third step experimental implementation (2) full-scale reading compares；
Method of this experiment can also slightly be made and change, for example, the low-voltage dc power supply (5), switch (7), rheostat (1), The second coil (4b) series connection of transformer (4) forms closed circuit, the first tertiary coil (4c) with transformer (4) of ammeter (2) Series circuit is formed, the first coil (4a) of ammeter (2) and transformer (4) is formed into series circuit in the 4th step；For another example, Tertiary coil (4c) series connection of the low-voltage dc power supply (5), switch (7), rheostat (1), transformer (4) forms closed circuit Scheme；If transformer (4) coil resistance value is larger, rheostat (1) can be omitted.
4. a kind of experimental method of electromagnetic induction experimental apparatus for researching as described in claim 1, which is characterized in that including following step It is rapid:
The first coil (4a) or the second coil (4b) or tertiary coil (4c) of the transformer (4), with small bulbs (3), switch (7), low-tension supply (5) series connection forms closed circuit；
The first coil (4a) of the first step, transformer (4) connects with small bulbs (3), closure switch (7) and is followed by low-voltage DC On source (5)；
Second step, closure switch (7) observe small bulbs (3) luminous situation；
Third step, disconnects switch, and low-voltage dc power supply (5) changes the approximately equal low-voltage alternating current power supply of voltage (5) into, re-closes Switch observes small bulbs (3) luminous situation；
4th step, A.C. voltmeter (6) measurement range selection exchange 20V, measure the voltage at small bulbs (3) both ends, observe alternating voltage The registration of table (6)；
5th step changes first coil (4a) into tertiary coil (4c), repeats step 1 to four；
6th step changes tertiary coil (4c) into the second coil (4b), repeats step 1 to four.
5. a kind of experimental method of electromagnetic induction experimental apparatus for researching as described in claim 1, which is characterized in that including following step It is rapid:
After the small bulbs (3) are in parallel with the first coil (4a) of transformer (4) or the second coil (4b) or tertiary coil (4c) It connects with low-tension supply (5), the low-tension supply (5) is low-voltage dc power supply；
The first step connects small bulbs (3) with after the parallel connection of the first coil (4a) of transformer (4) with low-tension supply (5)；
Second step, closure switch observe the brightness of small bulbs (3)；
Third step, disconnects switch, and observation disconnects moment small bulbs (3) luminous situation；
Coil in circuit is changed into the tertiary coil (4c) of transformer (4) by the 4th step, repeats to test；
Coil in circuit is changed into the second coil (4b) of transformer (4) by the 5th step, repeats to test.
6. a kind of experimental method of electromagnetic induction experimental apparatus for researching as described in claim 1, which is characterized in that including following step It is rapid:
The small bulbs (3) connect with rheostat (1) after with the first coil (4a) or the second coil (4b) of transformer (4) or Three-winding (4c) is in parallel, then connects with low-tension supply (5), and the low-tension supply (5) is low-voltage dc power supply；
The first step connects small bulbs (3) with after the parallel connection of the first coil (4a) of transformer (4) with low-voltage dc power supply (5)；
Second step, closure switch (7) observe the brightness of small bulbs (3)；
Third step, disconnects switch (7), and observation disconnects moment small bulbs (3) luminous situation；
4th step, it is in parallel with first coil (4a) of transformer (4) after small bulbs (3) are connected with rheostat (1), then with low pressure DC power supply (5) series connection, the slide plate of rheostat (1) are placed in resistance value close to maximum position, closure switch (7), mobile rheostat (1) Slide plate, keep small bulbs (3) brightness darker；
5th step disconnects switch (7), and observation disconnects moment small bulbs (3) luminous situation, can be with multioperation several times；
6th step changes the coil in the 4th step circuit tertiary coil (4c) into, repeats the experimental implementation of the four, the 5th steps；
7th step changes the coil in the 4th step circuit the second coil (4b) into, repeats the experimental implementation of the four, the 5th steps.
7. a kind of experimental method of electromagnetic induction experimental apparatus for researching as described in claim 1, which is characterized in that including following step It is rapid:
One coil of the transformer (4) connects low-voltage alternating current power supply (5), another coil string of small bulbs (3) and transformer (4) Connection, third coil are unloaded；
One coil of the first step, the transformer (4) connects low-voltage alternating current power supply (5)；
Second step, with the first binding post (401) and the second binding post (402) of A.C. voltmeter (6) difference measuring transformer (4) Between, it is defeated between third binding post (403) and the 4th binding post (404), between the 5th binding post (405) and the 6th binding post (406) Enter voltage or output voltage and record, whether analysis experimental data meets the transformation ratio formula of ideal transformer；
One coil of third step, the transformer (4) connects low-voltage alternating current power supply (5), the small bulbs (3) and transformer (4) The series connection of another coil, the zero load of third coil；
4th step, with the first binding post (401) and the second binding post (402) of A.C. voltmeter (6) difference measuring transformer (4) Between, it is defeated between third binding post (403) and the 4th binding post (404), between the 5th binding post (405) and the 6th binding post (406) Enter voltage or output voltage and records；Probe into prompt: after the input voltage for measuring transformer (4), predictable transformer once The big appointment of the voltage at two secondary coil both ends is how many, and the reality output electricity of two secondary coils is measured with A.C. voltmeter (6) It attempts to explain experimental data after pressure.
8. a kind of experimental method of electromagnetic induction experimental apparatus for researching as claimed in claim 2, which is characterized in that including following step It is rapid:
Ammeter (2) and a coil of transformer (4) are connected into closed circuit, in addition prepare two magnetism stronger identical Shape (cylinders such as cube or cylinder, thickness are thinner) magnet；
The first step, small range ammeter (2) and a coil of transformer (4) are connected into closed circuit；
Second step, is layered on the upper surface (shielding) of transformer (4) after taking Xiao Zhang's paper to fold, hand takes one piece of flaky magnet (one-pen cap is taken to erect, every time magnet lower edge and pen cap top phase when release in the certain eminence of transformer (4) overcentre Flat, or erected with objects such as graduated scales, magnet is discharged from same position every time) static release, pay attention to that magnet surface is allowed to protect Water holding falls to normal price on transformer (4), if it is not, please discharging again repeatedly, while observing the full-scale reading of ammeter (2) (partially Turn lattice number) and record；
Third step from the static release of transformer (4) overcentre same position after two pieces of flaky magnets are stacked, while observing electricity The full-scale reading of flow table (2) is compared with the full-scale reading of ammeter (2) in second step experimental implementation；
Ammeter (2) is changed to after being connected into closed circuit with another coil of transformer (4), two pieces of flaky magnets by the 4th step From the static release of transformer (4) overcentre same position, while the full-scale reading of ammeter (2) is observed, is tested with third step The full-scale reading comparison of ammeter in operation；Or one piece of flaky magnet is released from transformer (4) overcentre same position is static It puts, while observing the full-scale reading of ammeter (2), compared with the full-scale reading of ammeter in second step experimental implementation.
9. a kind of experimental method of electromagnetic induction experimental apparatus for researching as described in claim 1, which is characterized in that including following step It is rapid:
The first coil (4a) of transformer (4), switch, low-voltage dc power supply (5) are connected into closed circuit；The of transformer (4) One coil (4a) and tertiary coil (4c) are connected by switching (7) with low-voltage dc power supply (5) in the same direction or after reverse parallel connection；In addition Prepare the sheet metal of 1 or more lightweight；
The first step, the first coil (4a) of transformer (4), switch, low-voltage dc power supply (5) are connected into closed circuit；
Second step puts the sheet metal of 1 or more lightweight in transformer (4) upper face center areas adjacent；
Third step, quick-make switch, observation sheet metal have He Fanying, then disconnect switch；
4th step connects the first binding post (401) and the 5th binding post (405), the second binding post (402) and the 6th binding post (406) it connects, the first coil (4a) and tertiary coil (4c) of transformer (the 4) (electric current for latter two coil that is powered in parallel in the same direction Direction is consistent) it is connected afterwards by switching (7) with low-voltage dc power supply (5)；
5th step, closure switch (7), observation sheet metal have He Fanying, then disconnect switch；
6th step connects the first binding post (401) and the 6th binding post (406), the second binding post (402) and the 5th binding post (405) it connects, the first coil (4a) and tertiary coil (4c) reverse parallel connection (electric current for latter two coil that is powered of transformer (4) It is contrary) it is connected afterwards by switching (7) with low-voltage dc power supply (5)；It reclosing switch (7), observation sheet metal has He Fanying, Then disconnect switch.
10. a kind of experimental method of electromagnetic induction experimental apparatus for researching as described in claim 1, which is characterized in that including following Step:
In addition the enameled wire prepared puts in the gap of transformer (4), and one encloses on the iron core for being wound on transformer (4) side, paint Envelope curve length is proper between 1 meter to 2 meters, and a certain coil of transformer (4) passes through switch (7) and low-voltage alternating current power supply (5) Series connection；
The first step, is respectively scraped off the paint at enameled wire both ends with pocket knife a bit of, and one of enameled wire is put between transformer (4) Gap, one encloses on the iron core for being wound on transformer (4) side, completely around ten multi-turns (circle number depending on enamel-cover line length), two Head is placed on insulated platform；
Second step, a certain coil of transformer (4) are connected with low-voltage alternating current power supply (5) by switching (7), are powered on, with friendship Ampere-voltage meter (6) successively measures the input voltage at this coil both ends of transformer (4) and the output voltage at enameled wire both ends.
CN201910357642.XA 2019-04-29 2019-04-29 A kind of electromagnetic induction experimental apparatus for researching and its experimental method Pending CN110148338A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110412329A (en) * 2019-09-04 2019-11-05 广东电网有限责任公司 A kind of test macro and method of the alternation effect of ac circuit

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110412329A (en) * 2019-09-04 2019-11-05 广东电网有限责任公司 A kind of test macro and method of the alternation effect of ac circuit

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