Question

If you touch the two terminals of a power supply with your two fingertips on opposite hands, the potential difference will produce a current through your torso. The maximum safe current is approximately 5 {\rm mA}.If your hands are completely dry, the resistance of your body from fingertip to fingertip is approximately 500 {\rm k\Omega}. If you accidentally touch both terminals of your 120 {\rm V} household electricity supply with dry fingers, will you receive a dangerous shock?If your hands are moist, your resistance drops to approximately 1 {\rm k\Omega}. If you accidentally touch both terminals of your 120 {\rm V} household supply with moist fingers, will you receive a dangerous shock?

Answer 1

Answer:

Yes the body will receive a dangerous shock in both cases.

Explanation:

Different parts of the body has different resistance. skin has the high resistance as compared to other organs of the body.

Dry skin has high resistance than wet skin this is because water is relatively good conductor of electricity, it adds parallel path to the current flow and hence reduces skin resistance.

Dry hands body has approximately 500 kΩ resistance and if 120 V electricity supply current received will be:

I = V/R= 120/ 500*10^3

I= 0.24 mA

Even the current seems is much lower than the safe zone but this is the case in case of DC voltage in case of AC voltage the body will receive a shock this is because the skin pass more current when the voltage is changing i.e. AC.

Similarly for wet hands body resistance is 1 kΩ. so the current through the body seems to be:

I = 120 / 1000

I = 12 mA

The current is higher than safe zone so the body will receive a dangerous shock.