Faraday’s Solenoid Experiment

When magnet is stationary inside or outside the solenoid, no deflection of galvanometer pointer.
When magnet is inserted into the solenoid, the galvanometer pointer deflects in one direction. 
When magnet is withdrawn from the solenoid, the galvanometer pointer deflects in opposite direction.
To help you understand this better, you can play with the applet below.
Steps
  1. Simply place the magnet stationary inside or outside the coil. You should not see any deflection in the galvanometer.
  2. At the moment, you move the magnet towards the coil, you should be able to see the pointer deflects in one direction. Note that it is no necessarily for you to move the magnet into the coil, you can move it below or above the coil as well. You should get the same result but with smaller deflection. Try it now!
  3. When you move the magnet out from the coil, you should be able to see the pointer deflects in the opposite direction.
Conclusion:

When there is a relative motion between the solenoid and the magnet, there is an induced emf, which drives an induced current such that the galvanometer pointer deflects.

Note:
  • The deflection of pointer is momentary deflection, which means the pointer kicks to a value then come back to central position (value of 0).
  • There is an induced current ONLY when the circuit is CLOSED! But emf is always induced whenever there is a relative motion.
  • Also, there are two ways to do this experiment:
  1. Fixing solenoid and moving magnet
  2. Fixing magnet and moving solenoid
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