A DEMONSTRATION OF FARADAY’S LAW OF INDUCTION
This demonstration literally shows the Faraday’s law dF\dt = -e (t) where F(t) is the magnetic flux and e (t) is the induced voltage.
What you need:
1) Two coils, one with ca 500 windings, one with ca 1000 windings. These numbers
are not all that important. They are the ones I used and they gave good results.
The main thing is that it should be a rather big difference in the number of windings.
2) A two-channel oscilloscope.
3) An iron bar long enough to stick through both coils simultaneously.
4) Cables and plugs
5) A signal-generator
What to do:
1) You connect the signal-generator to the biggest coil .
2) This coil you also connect to one of the channels on this scope.
3) The smaller coil you connect to the other scope-channel
4) Place the smaller coil onto of the biggest one and place the iron bar inside both coils.
5) Send a triangular low voltage through the big coil and adjust the scope-settings so you get a clear signal on this channel.
6) Then adjust the settings for the other channel.
7) Hopefully you will now have a rectangular voltage on this channel. (Most likely it will be somewhat fuzzy, but hey we did it…..)
8) If you change your input-signal to a sine-form, your output will be a cosine-form.
The ac-voltage in the big coil induces a variable magnetic field through both coils.
This mag.field will be in phase with the ac-voltage.
The variable magnetic field in turn induces an ac-voltage in the second coil, which will be 180 deg out of phase with the mag field because of Faradays law.
In other words, the signal-curve from the small coil will be the negative time-derivative of the signal-curve fed to the big coil.