Question

The resistance of physiological tissues is quite variable. The resistance of the internal tissues of humans, primarily composed of salty solutions, is quite low. Here the resistance between two internal points in the body is on the order of 100 ohms. Dry skin, however, can have a very high resistance, with values ranging from thousands to hundreds of thousands of ohms. However, if skin is wet, it is far more conductive, and so even contact with small voltages can create large, dangerous currents though a human body. (For example, although there is no specific minimum current that is lethal, currents generally exceeding a couple tenths of Amps may be deadly.)

Assuming that electrocution can be prevented if currents are kept below 0.1 A, and assuming the resistance of dry skin is 100,000 ohms, what is the maximum voltage with which a person could come into contact while avoiding electrocution? (Of course, all bets are off and things become far more dangerous if this person's skin is wet, which can reduce the resistance by more than a factor of 100.)

Answer 1

Given Information:

Current = I = 0.1 A

Resistance = R = 100 kΩ

Required Information:

Voltage = V = ?

Answer:

Voltage = V = 1000 V

Step-by-step explanation:

We know that electrocution depends upon the amount of current flowing through the body and the voltage across the body.

V = IR

Where I is the current flowing through the body and R is the resistance of body.

If electrocution can be avoided when the current is below 0.1 A then

V = 0.1*10×10³

V = 1000 Volts

Therefore, 1000 V is the maximum voltage with which a person could come into contact while avoiding electrocution, any voltage more than 1000 V may result in fatal electrocution.

Also note that human body has very low resistance when the body is wet therefore, above calculated value would not be applicable in such case.