Interactive Physics Simulation

Electron Drift vs. Field Speed

Two Very Different Velocities Inside One Wire

Close the switch and a lamp meters away lights up almost instantly — because the electric field propagates through the conductor at a large fraction of the speed of light. But the electrons that actually carry the current only drift at a snail's pace, nudged along by that field. Adjust the current and wire size below and compare both speeds directly.

Current — 10 A

Wire Cross-Section

Wire Length

Show energy flow (Poynting vector)

The Switch & the Lamp

This is a closed-loop circuit — close the switch and current keeps flowing continuously around it (no reset needed) until you open the switch again. The initial wavefront sweep is compressed to be watchable — the real transit time is shown below, calculated from your chosen wire length.

Field Speed2.05×10⁸ m/s

Field Reaches Lamp In–

Drift Velocity–

Electron Would Take–

Lamp is lit. How far did one electron actually move?

–

≈ – — vanishingly small compared to the wire's 100 m length.

Inside the Copper Lattice

Fixed Cu²⁺ ions (orange) form the lattice; free electrons (blue) jitter randomly at rest and gain a slow net drift once the switch closes — cross-section: 2.5 mm².

Same Event, Two Velocities (log scale)

Electric Field / Energy Propagation–

Electron Drift Velocity–

Bars are on a logarithmic scale (10⁻⁵ to 10⁹ m/s) — on a linear scale the drift bar would be invisible.