Final answer:
Electrical shocks can be used to elicit a biological response, with effects varying depending on current, path, duration, and frequency. Higher frequencies lead to less nerve sensitivity, while high currents through the heart can cause fatal arrhythmias and burns.
Step-by-step explanation:
A brief heat shock or electrical shock is used to stimulate a biological response. The passage of current through the body affects various physiological processes. For example, an electrical current can be used in medical treatments, such as stimulating muscle action in paralyzed limbs or treating heart arrhythmias with a pacemaker. However, the effects of an electrical shock depend on several factors, including the amount of current, path of current, duration, and the frequency of the alternating current (AC).
Specifically, the body's sensitivity to electric shocks varies with frequency. At standard 50- or 60-Hz, which are common in household power, the body is very sensitive to current. As the frequency increases beyond this range, the body becomes less sensitive to the effects on nerves. Very high-frequency currents can be used for medical purposes, such as removing warts, without significantly affecting other tissues like the heart. On the other hand, high currents passing through the heart can cause ventricular fibrillation, which is often fatal. Therefore, the threshold for such dangers occurs between 100 and 300 mA. Above approximately 300 mA, current can also cause burns depending on its concentration.