How do defibrillators work (in terms of physics)?

Question

How do defibrillators work (in terms of physics)?

Answer 1

A defibrillator typically has a circuit in which a high voltage source is used to charge a large capacitor.  When the defibrillator delivers a shock to the heart, a switch is flipped and the charged capacitor becomes part of an RC circuit which includes the heart as a "resistor."  When this happens, the build up of charge in the capacitor discharges and produces a particular voltage wave form across the heart that is ideal for restoring proper rhythm to the heart.