No, the velocity of a charged particle in an electric field does not always remain constant. The velocity of a charged particle in an electric field depends on various factors, including the strength and direction of the electric field, the initial velocity of the particle, and other forces acting on the particle.
When a charged particle is subjected to an electric field, it experiences a force called the electric force. The electric force can cause the charged particle to accelerate, leading to a change in velocity.
If the electric field is constant and the particle is only under the influence of the electric field (neglecting other forces like gravity or magnetic fields), the charged particle will undergo constant acceleration due to the electric force. In this case, the velocity of the particle will change over time.
However, if the electric field is uniform and the charged particle reaches a steady state, where the electric force is balanced by other forces (such as friction or magnetic force), the velocity of the particle can become constant. In such cases, the charged particle moves with a constant velocity called the terminal velocity.
It's important to note that the behavior of charged particles in electric fields can be more complex if other factors or forces are involved. For example, if magnetic fields are present, charged particles can experience a combination of electric and magnetic forces, resulting in curved or spiral trajectories rather than constant velocities.