1. Your car battery is dead, and your friends are helping you start your car wit

Question

1. Your car battery is dead, and your friends are helping you start your car with cheap jumper cables. One cable carries current from their car to your car, and a second cable returns that current to their car. As you try to start your car, a current of 60 A flows through the cables to your car and back, and a voltage drop of 4 V appears across each cable. What is the electric resistance of each jumper cable?

2. Your car battery is dead, and your friends are helping you start your car with cheap jumper cables. One cable carries current from their car to your car, and a second cable returns that current to their car. As you try to start your car, a current of 90 A flows through the cables to your car and back, and a voltage drop of 2 V appears across each cable. If you replace the cheap cables with cables having half their electric resistance, what voltage drop will appear across each new cable if the current doesn

Explanation / Answer

here R = resistance V = voltage difference I = current

1) R = V/I = 4/60 = 0.067 ?

2) R = V/I = 2/90 = 0.022 ?
R/2 = 0.011 ?
V = IR = (90)(0.011) = 1 V

3) power = V * I= 300000 * 1400 = 420000000 amp-volt = 42000 kilo A-V

4) resistance offered by wires R = V/I = 400000/500 = 800 ohm

now current through homes is (i) = voltage difference accross homes/ resistance= V/R = 120 / 800 = 0.15 ampere

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