A particle is released from the origin with a velocity `vhate(i)`. The electric field in the region is `Ehate(i)` and magnetic field is `Bhat(k)`. Then

Options

A. If `v=0 and E=0` then particle will execute a circular path.
B. If `v=0, E!=0` then particle is positively charged then it executes clockwise
C. If `v=0` and `E != 0` then the particle will execute a cycloidal motion in the x-y plane.
D. If `vgt0` and `E!= 0` and the particle is positievely charged and `Bgt0` then the particle wil excute anticlockwise anticlock wise circle as seen from +z direction.

Answer

C, D

Explanation

if `v=0,E=0` then no force will act on particle, hence partcle remains at rest
(b) here `v=0, E!=0`, due to E the particle will gain velocity in x direction. Due to this velocity it will experience force due to magnetic field along negative y axis. As a result of it, the particle will move in curved path that will not be a circle.
(c) If `v=0,E!=0`, then particle will execute cycloidal motion.
(d) If `E=0`, then path will be circular.