Q. A charged particle of mass $m$ and charge $q\ $is released from rest in an electric field of constant magnitude$E$. The kinetic energy of the particle after time $t$ is
A) $\frac{E^{2}q^{2}t^{2}}{2m}$
B) $\frac{2\ E^{2}t^{2}}{qm}$
C) $\frac{E\ q^{\ }m}{2t}$
D) $\frac{Eq^{2}m}{2t^{2}}$
Explanation
(a) Here, $u = 0,a = \frac{F}{m} = \frac{qE}{m}$
$v = u + at = 0 + \frac{qE}{m}t$
KE $\frac{1}{2}mv^{2} = \frac{mq^{2}E^{2}t^{2}}{2m^{2}} = \frac{E^{2}q^{2}t^{2}}{2m}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.