Final answer:
Defibrillators avoid causing serious burns because the skin effectively conducts electricity at high voltages used in these devices and the gel used aids in energy transfer to the heart without skin absorption.
Step-by-step explanation:
A defibrillator does not cause serious burns due to the fact that human skin is a good conductor of electricity at high voltages, which is the level at which defibrillators operate. To assist the transfer of energy safely to the heart, a special gel is used that helps this energy bypass the skin without being absorbed. Instead, the energy passes through to the heart, where it can help restore a normal heartbeat pattern in cases of ventricular fibrillation, an often fatal condition due to a lack of blood circulation.