Physics – 2.3.1 Conduction | e-Consult

When a potential difference (voltage) is applied across a metallic conductor, an electric field is established within the conductor. This electric field exerts a force on the free (delocalised) electrons present in the metal. Free electrons are electrons that are not tightly bound to individual atoms and can move throughout the metallic structure.

The electric field causes these free electrons to drift in a specific direction, typically from the negative terminal to the positive terminal. This directed movement of charge constitutes an electric current. The electrons are constantly colliding with the metal ions in the lattice structure. However, the collisions are relatively infrequent and the net effect is a continuous drift velocity of the electrons in the direction of the electric field. The magnitude of this drift velocity is proportional to the electric field strength and inversely proportional to the electron density and the cross-sectional area of the conductor. A larger potential difference results in a stronger electric field, leading to a greater drift velocity and thus a larger current. The delocalised nature of the electrons is crucial; if electrons were tightly bound to individual atoms, they would not be able to move freely in response to the electric field, and electrical conduction would be significantly reduced or absent.