A flat coil ABCD is freely suspended between the pole pieces of a U-shaped permanent magnet with the plane of coil parallel to the magnetic field.

(a) What happens when a current is passed in the coil?

(b) When will the coil come to rest?

(c) When will the couple acting on the coil be (i) maximum, (ii) minimum?

(d) Name an instrument which makes use of the principle stated above.

A coil ABCD mounted on an axle is placed between the poles N and S of a permanent magnet as shown in figure.

(a) In which direction will the coil begin to rotate when current is passed through the coil in direction ABCD by connecting a battery between the ends A and D of the coil?

(b) Why is a commutator necessary for the continuous rotation of coil?

(c) Complete the diagram with commutator, etc. for the flow of current in the coil.

Electromagnetic induction is the phenomenon in which emf is induced in the coil if there is a change in the …………… linked with the coil.

1. force
2. electric flux
3. magnetic flux
4. all of the above.

Electromagnetic induction is based on :

1. Faraday's law
2. Lenz's law
3. Right hand thumb rule
4. Fleming's left hand rule