question_answer

A rectangular loop of wire, supporting a mass m, hangs with one end in a uniform magnetic field \[\overset{\to }{\mathop{\operatorname{B}}}\,\] pointing out of the plane of the paper. A clockwise current is set up such that i > mg/Ba, where a is the width of the loop. Then:                               [JEE ONLINE 23-04-2013]

A) The weight rises due to a vertical force caused by the magnetic field and work is done on the system.

B) The weight do not rise due to vertical for caused by the magnetic field and work is done on the system.

C) The weight rises due to a vertical force caused by the magnetic field but no work is done on the system.

D) The weight rises due to a vertical force caused by the magnetic field and work is extracted from the magnetic field.