Capacitors & RC Circuits

Watch exponential charging and discharging governed by the RC time constant

A capacitor stores charge on two parallel plates separated by a dielectric. Its capacitance C = ε₀A/d depends on plate area A and separation d. In an RC circuit, charging follows V(t) = V₀(1 − e^(−t/RC)) and discharging follows V(t) = V₀e^(−t/RC). The time constant τ = RC is the time to reach approximately 63% of the final voltage during charging, and the energy stored at full charge is U = ½CV².