Motion of a Charged Particle in a Uniform Electric Field —
When a charged particle of charge $q$ moving or at rest is subjected to a uniform electric field $\vec{E}$, the force acting on it is
$\vec{F}=q \vec{E}$
The direction of $\vec{F}$ is same as that of $\vec{E}$, if $q$ is positive and $-\vec{E}$ if $q$ is negative.
