Animation showing the Drude current density response.

The Drude Model of Electrical Conduction

Animation showing the motion of a particle driven by a wave, illustrated through a sequence of blue points at increasing values of ωt. As the wave propagates leftward, the particle’s trajectory curves, with positions labeled for ωt = 0.2, 0.5, 1.0, 2.0, and 5.0. The frames highlight how the particle’s displacement evolves over time under a traveling wave, demonstrating oscillatory motion and phase progression.

The Drude model is one of the earliest attempts to explain how electricity flows inside metals.

It imagines the metal as a collection of positively charged ions with a “gas” of free electrons moving around between them. These electrons behave a bit like tiny billiard balls bouncing around randomly.

When no electric field is applied, the electrons move in all directions with no net flow.

But when you apply a voltage, the electric field gently pushes the electrons so that, on average, they drift in one direction.

This slow drift of many electrons is what we call an electric current.

The Drude model also explains resistance.

As electrons move through the metal, they frequently collide with the vibrating ions. Each collision interrupts their motion, slowing them down.

More collisions mean higher resistance.

This is why resistance increases with temperature: hotter atoms vibrate more, causing more electron scattering.

Even though the Drude model is simple and treats electrons like classical particles, it captures many important features of electrical conduction, such as Ohm’s Law, and laid the foundation for more advanced quantum models that came later.