Question

A charged particle of mass m and charge q is released from rest in a uniform electric field E. Neglecting the effect of gravity, the kinetic energy of the charged particle after t second is

• A.
• B.
• C.
• D.

Answer 1

The correct option is B

The acceleration is: $a=\frac{qE}{m}$

Also, $v=u+at$

$v=0+\frac{qE}{m}t$

$v=\frac{qE}{m}t$

The kinetic energy is

$k=\frac{1}{2}m{v}^2$

$k=\frac{1}{2}m(\frac{qE}{m}t{)}^2$

$k=\frac{q^2{E}^2{t}^2}{2m}$