An electron is projected at an angle `theta` with a uniform magnetic field. If the pitch of the helical path is equal to its radius, then the angle of projection is

Options

A. `tan^(-1)pi`
B. `tan^(-1)2pi`
C. `cot^(-1)pi`
D. `cot^(-1)2pi`

Answer

B

Explanation

`I=(mv sin theta)/(qB),` Pitch, `p=v cos theta T=v cos theta(2pim)/(qB),` Now p=r, solve to get `theta =tan^(-1)2pi`