In the below figure, an electron of mass m, charge-e, and low(negligible) speed enters the region between two plates of potential difference V and plate separation d, initially headed directly toward the top plate. A uniform magnetic field of magnitude B is normal to the plane of the figure. Find the minimum value of B such that the electron will not strike the top plate.

Options

A. `sqrt((2mV)/(ed^(2))`
B. `sqrt((mV)/(2ed^(2))`
C. `sqrt((mV)/(ed^(2))`
D. `2sqrt((mV)/(ed^(2))`

Answer

B