A person with body resistance between his hands of 10k? accidentally grasps the
ID: 1319652 • Letter: A
Question
A person with body resistance between his hands of 10k? accidentally grasps the terminals of a 14-kV power supply.
Part A
If the internal resistance of the power supply is 1800? , what is the current through the person's body?
Express your answer using two significant figures.
Part B
What is the power dissipated in his body?
Express your answer using two significant figures.
Part C
If the power supply is to be made safe by increasing its internal resistance, what should the internal resistance be for the maximum current in the above situation to be Imax=1.00mA or less?
Express your answer using two significant figures.
Explanation / Answer
V = 10 KV = 10000V
Net resistance = 10000 + 1800 = 11800 ohm
a)So current ,I = 10000/11800 = 0.85 A (ans)
b) Power dissipated ,P =I^2R = 0.85*0.85*10000 = 7225 W (ans)
c)Let internal resistance =r
I = V/(R+r) = 10000/(10000 + r) <=0.001
10 + 0.001r > = 10000
0.001r> = 9990
r>=9990000 ohm
Minimum value of internal resistance = 9990000 ohm =9990 Kohm (ans)
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