Question

A charge is particle is force to move in electric field will an always move along the electric linear of force?

Answer 1

Depending on the type of a charged particle, its charge can be either positive (for example, a proton) or negative (for example, an electron). As long as the Coulomb force can be defined as

$$\vec{F} = q \vec{E}$$

where q is the charge of a particle and \vec{E} is the electic field vector. Assuming that it is the only force acting on the particle, we obtain:

$$q \vec{E} = m \vec{a},$$

where \vec{a} is the acceleration of a particle.

Hence, the direction of a Coulomb force and the acceleration of a particle (i.e. direction of its motion in the absence of other forces) coincide in case of positively (q>0) charged particles and are antiparallel in case of negatively (q<0) charged particles.