Question

A flat coil ABCD is freely suspended between the poles 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, and (ii) minimum ?
(d) Name an instrument which makes use of the principle stated above.

Answer 1

(a)The coil will experience a torque due to which it will rotate.
(b) The coil will come to rest when their plane become normal to the magnetic field.
(c) (i) When plane of a oil is parallel to the magnetic field, (ii) When plane of coil is normal to the magnetic field.
(d) The instrument which makes use of the principle stated above is d.c. motor.