Question
A particle of mass M and charge Q moving with velocity v describes a circular path of radius R when subjected to a uniform transverse magnetic field of induction B. The work done by the field, when the particle completes one full circle, is
zero
Solution
B.
zero
When particle describes circular path in a magnetic field, its velocity is always
perpendicular to the magnetic force
Power P = F . v
P = Fv cosθ
Hence
P = 0
But P =
W = P .t
Hence, work done W = 0 (everywhere)
