Question

A conducting ring of mass 2 kg and radius 0.5 m is placed on a smooth horizontal plane.The ring carries a current i= 4A. A horizontal magnetic field B = 10 T is switched on at time t = 0 as shown in figure. The initial angular acceleration of the ring will be

(A) 40π rad/s² 

(B) 20π rad/s²

(C) 5π rad/s² 

(D) 15π rad/s² 

Answer 1

Correct option: (A) 40π rad/s²

Explanation:

As we know, if a coilor a closed of any shape is placed in uniform electric field, magnetic force on the coil or the loop is zero.

So, the centre of mass of the coil remains in rest. the torque on the coil is