There is region of space where uniform magnetic field of induction B exists. The field exists at all points for which `x-` coordingates are positive. The direction of field ia along negative z axis.
Now a certain charged particle of mass m and charge q a certain speed enters in this region. A magnetic field at a point whose coordinates are `x=0,y=-d` and `z=0` . Magnetic force will start acting on the particle and particle moves in a uniform circular motion, such that origin becomes centre of circular path described by it
The speed of the charge particle will be

Options

A. `(qB)/(m)`
B. `(qd)/(m)`
C. `(qbd)/(2m)`
D. `(qBd)/(m)`

Answer

D

Explanation

Radius of circular path will be equal to `d=(mv)/(qB)impliesv=(qBd)/(m)`