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Explain the phenomenon of electromagnetic induction. Describe an experiment to show that a current is set up in a closed loop when an external magnetic field passing through the loop increases or decreases.
The process in which a in a conductor induces a current in is called Electromagnetic induction.
The current produced is called the and the potential difference set up is called the .
Experiment to show that a current is set up in a closed loop when an external magnetic field passing through the loop increases or decreases:
Steps:
- Take two different coils of copper wire with a large number of turns (say \(50\) and \(100\) turns, respectively) and insert them over a non-conducting cylindrical roll, as shown in the below figure (You may use a thick paper roll).
Current is induced in coil-2 when current in coil-1 is changed.
- Connect the coil-1, which has a larger number of turns, in series with a battery and a plug key. Also, connect the other coil-2 with a galvanometer, as shown in the figure.
- Plug in the key. Notice the galvanometer.
Observation:
You will see that the needle of the galvanometer and just as , indicating a in coil-2.
Disconnect coil-1 from the battery.
You will see that the needle momentarily moves but to the . It indicates that now the current flows in the in coil-2.
This shows that there is current in coil-2 whenever there is .
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