Materials required : Wooden base, soft iron cylinder, copper wire, metal ring,
AC source, DC source, switch.
1) Take wooden base fix a soft iron cylinder on the wooden base vertically.
2) Wind copper wire around the soft iron.
3) Now take a metal ring which is slightly greater in radius than the radius of soft iron cylinder and insert it through the soft iron cylinder on the wooden base.
4) Connect the ends of the coil to the AC source and switch on the current.
5) You may notice that metal ring is levitated on the coil.
6) Switch off the current, the ring will jump into the air very dramatically.
7) Remove the AC supply and connect a DC supply.
8) The metal ring levitates because the net force on it is zero.
9) The levitation of metal ring is possible only when the metal ring should behave like a magnet and should change its polarities in the some intervals but in a sense opposite to that of the solenoid.
10) When switch is on with DC supply there should be a change in flux linked ring.
11) Whenever there is a continuous change of magnetic flux linked with closed coil the current is generated in the coil. It is Faraday's law.
Precautions : Take care when the metal ring is leviated from the cylinder.