Final answer:
To prevent shock, high frequency currents are used because the body becomes less sensitive at these frequencies, allowing current to stay on the skin's surface. Electrical safety devices utilize this principle to minimize injury risks, such as modern pulsed electric fences that prevent sustained shocks.
Step-by-step explanation:
To prevent shock using high frequency, the current is turned on gradually. As frequency increases, the body's sensitivity to electrical currents decreases, especially in nerves. At very high frequencies, electrical current tends to travel only on the skin's surface. This is why high frequency current can be used in medical procedures, such as removing warts, without affecting deeper structures like the heart. Electrical safety systems utilize this principle by employing high frequencies and low currents to reduce the severity of electric shocks.
Electrical safety devices often incorporate techniques to minimize the duration and path of electrical currents to prevent serious injuries. Modern electric fences, for instance, use pulsed currents to allow a person to withdraw from contact, reducing the risk of a sustained shock that could cause muscular contractions or ventricular fibrillation.