If you touch the two terminals of a power supply with your two fingertips on opp
ID: 1364050 • Letter: I
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 mA.
(a) If your hands are completely dry, the resistance of your body from fingertip to fingertip is approximately 530 k. If you accidentally touch both terminals of your 120 V household electricity supply with dry fingers, what current will flow, and will you receive a dangerous shock?
____________mA, a ---Select--- dangerous harmless shock.
(b) If your hands are moist, your resistance drops to approximately 1.8 k. If you accidentally touch both terminals of your 120 V household supply with moist fingers, what current will flow, and will you receive a dangerous shock?
________ mA, a ---Select--- dangerous harmless shock.
(c) For the situation of part a, what electric power is dissipated in your body?
___________mW
Would you notice the heating?
Yes No
Explanation / Answer
a )
first case I = V/R = 120/530*103 = 0.22 mA safe harmless
second case
b ) I = V/R = 120/1 .8 *103 = 66.67 mA not safe dangerous shock
c) electric power is dissipated in your body P = V*I = 120* 0.22 *10-3 = 27.2 m W
d ) No we will not notice heat our body tempreture more then this can rise