- #1
purple_prize
- 3
- 0
A non conducting ring of mass m and radius R has a charge Q uniformly distributed over its circumference. This ring is placed on a rough horizontal surface such that the plane of the ring is parallel to the surface. A vertical magnetic field B=B0t2 τ is switched on. After 2 second from switching on the magnetic field, the ring is just about to rotate around vertical axis through its centre. Then
( A ) The induced electric field is quadratic in time "t"
( B ) The force tangential to the ring is B0QRt
( C ) Until 2 seconds, the friction force does not come into play
( D ) The friction coefficient between the ring and the surface is {2B0RQ}/{mg}
Answer - B and D.
Can anyone please make me clear about WHY the ring is about to rotate and solve the question properly? I can't understand the problem clearly.
( A ) The induced electric field is quadratic in time "t"
( B ) The force tangential to the ring is B0QRt
( C ) Until 2 seconds, the friction force does not come into play
( D ) The friction coefficient between the ring and the surface is {2B0RQ}/{mg}
Answer - B and D.
Can anyone please make me clear about WHY the ring is about to rotate and solve the question properly? I can't understand the problem clearly.