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AS · Topic 9

The flow of charge.

Current as a stream of charge carriers drifting through a conductor, the potential difference that pushes them and the power they deliver, and the resistance and resistivity that resist them. Watch I = Anvq link microscopic drift to macroscopic current, and trace the I–V curves that betray a conductor, a diode and a filament lamp. Play the simulations below, then work the gamified lessons, the Paper 1 practice and the concept map.

Simulations · live
Interactive · live Charge carriers and drift velocity Tune the carrier density, area and drift speed and watch I = Anvq set the current as electrons crawl through the lattice. Loads only when you launch, so the page stays fast.
Interactive · live Current-voltage characteristics Sweep the voltage across a metallic conductor, a diode and a filament lamp and watch each I–V curve take its tell-tale shape. Loads only when you launch, so the page stays fast.
Interactive · live Electrical power dissipation Adjust the current, voltage and resistance and see P = VI, P = I²R and P = V²∕R agree on the power dissipated. Loads only when you launch, so the page stays fast.
Interactive · live Resistance and resistivity Stretch the wire and change its area to watch R = ρL∕A reshape the resistance while the material's resistivity stays fixed. Loads only when you launch, so the page stays fast.
Paper 1 practice · live
Multiple-choice · Paper 1 style Topic 9 Paper 1 practice A set of original multiple-choice questions across charge carriers, potential difference and power, resistance and resistivity. Open practice →
Lessons · live
Electric current and charge carriers → Potential difference and electrical power → Resistance and resistivity →
Concept map
Open the concept map →