A particle of mass M and charge Q moving with velocity v describe 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 :

Options

A. `((mv^(2))/R)2piR`
B. Zero
C. `BQ2piR`
D. `BQv2piR`

Answer

B

Explanation

When particle describes circular path in a magnetic field, its velocity is always perpendicular to the magnetic force.
Power `P=F.v=Fv cos theta `
Here `theta=90^(@) :. P=0,` But`P=W/timpliesW=P.t`
Hence, work done, W = 0 [everywhere]