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current and resistance In the circuit shown, each of the resistors can dissipate

ID: 3893067 • Letter: C

Question

current and resistance

In the circuit shown, each of the resistors can dissipate a maximum of 1.0 watts before they are damaged by heat. What is the maximum voltage (EMF) of the battery that will not destroy any of the resistors? The bulk resistivity rho of a human being is about 5 ohm-meters. (This doesn't include the contact resistance of the skin.) Consider using each of your hands to grab the two ends of a battery. Consider the conducting path between your two hands to be roughly a cylinder that is 10 centimeters in diameter and 1.6 meters in length. Suppose that your hands are sweaty, so that there isn't much skin resistance. Compute the resistance between your two hands, ignoring skin resistance. What battery voltage would prove lethal, assuming that it takes a current of about 0.1 amp to stop your heart? With the current used in part (b), what is the electrical power dissipated in your body?

Explanation / Answer

Solution:

3)

As there are 10 resistors, so max power dissipated by the resistors is 10 watts

We know that power, P_max = I^2 * R_equ


R_equ = (25+30)+(25||15||(10 + (20||20)) + 40 +(50||50)

R_equ = (55) + (25 || 15 || (10 + 10)) + 40 + 25

= 120 + (25 || 8.57)

= 126.38 ohm


hence I^2 = 10 / 126.38 = 0.079125

I = 0.2813 A


But we know that V = I*R_equ

V = (0.2813A)(126.38 ohm) = 35.55 v