Without a given potential, how do free electrons in a conductor constantly move?

The movement of free electrons in a conductor without an applied electric potential primarily occurs in a random manner. In the absence of an electric field, these electrons are not influenced by any external forces, which leads to their zigzag motion as they collide with atoms in the material. This chaotic movement is a result of thermal energy and temperature, causing the electrons to vibrate and scatter around in all directions.

When a potential is applied across the conductor, this random movement is modified, and the electrons begin to drift in a directed manner towards the positively charged end of the circuit, leading to a net current flow. However, without an applied voltage, the electrons do not have a preferred direction and continue to move randomly.

The other options do not accurately describe the behavior of free electrons in a non-driven state. Circular movement implies a specific directional or rotational motion, which does not occur without external influences. One-directional movement would only occur under the influence of an electric potential. Constant speed suggests uniform motion, whereas electrons experience varying speeds due to random collisions. Therefore, the correct understanding hinges on their intrinsic random motion in the absence of an external electric field.