Spark image

The discharge of a capacitor

The animation shows the discharge of a capacitor. By using the slider you can change the value of the resistor through which the capacitor discharges (100 Ω or 200 Ω). It is best to do this before running the animation.

For the moment please use f5 to reset the animation.

The current (I) in the discharge at an instant is:
I = - dq/dt
But V = IR and q = CV so dq/dt = d(CV)/dt = C dV/dt
Therefore we have V = -CR dV/dt

Rearranging and integrating gives:

Capacitor discharge (voltage decay): V = Voe-(t/RC)
© Keith Gibbs/John Bourne 2016