How a capacitor holds charge, how capacitors combine, the energy locked in the field, and the exponential way a capacitor discharges. Play the three simulations below. The gamified lessons and the topic Paper 4 practice are live below too.
Simulations · live
Interactive · liveCapacitors and capacitanceC = Q/V for a single capacitor, plus series and parallel combinations with the stored charge shown.Loads only when you launch, so the page stays fast.
Interactive · liveEnergy stored in a capacitorThe triangle under the V-Q graph, with the energy as ½QV = ½CV² updating as you change C and V.Loads only when you launch, so the page stays fast.
Interactive · liveDischarging a capacitorExponential decay of charge through a resistor, with the time constant τ = RC marked at the 37% point.Loads only when you launch, so the page stays fast.
Paper 4 practice · live
Structured questions · with worked solutionsTen original Paper 4 style questionsA full topic set across capacitance, energy stored, and discharge, with questions linking the lessons within the topic and full worked solutions.Open practice →