The electric force $\mathbf{F}$ experienced by a charge $q$ in a uniform electric field $\mathbf{E}$ is given by $\mathbf{F} = q\mathbf{E}$. For an electron, the magnitude of the force is $F = eE$. According to Newton's second law of motion, the force is also equal to the product of mass and acceleration ($F = ma$). Equating the two expressions for force ($ma = eE$), the acceleration $a$ is given by $a = \frac{eE}{m}$ . This acceleration is constant and directed opposite to the electric field for a negatively charged particle like an electron.