Final answer:
In a uniform electric field, a negative charge moves from high potential to low potential, in the opposite direction of the electric field lines. This results in motion in a straight line. However, in a magnetic field, the charged particle may experience circular motion instead.
Step-by-step explanation:
If a negative charge is released in a uniform electric field, it will move from high potential to low potential. This movement is due to the fact that the electric field lines point from positive to negative charge. In the case of a negative charge, the force it experiences due to the electric field is in the direction opposite to the field lines. Therefore, a negative charge will move toward the higher potential, which is the opposite direction of the electric field lines.
In more general terms, the direction of the electric field is always in the direction where the electric potential V decreases. The magnitude of the electric field E equals the rate of decrease of V with distance. Hence, if we have a uniform electric field, the direction and magnitude of the force on a charge will be constant, leading to motion in a straight line. This is true for both positive and negative charges, with negative charges moving in the opposite direction to positive ones.
However, in cases involving magnetic fields, a charged particle moving through a magnetic field that is perpendicular to its velocity will experience a force perpendicular to its motion, resulting in uniform circular motion, not straight-line motion. This contrasts with the motion in an electric field and is important to differentiate.