A dead battery is charged by connecting it to the live battery of another car wi

Question

A dead battery is charged by connecting it to the live battery of another car with jumper cables (see figure). (Take R = 1.30 and r = 0.08 . For this problem, if your answers are used in any subsequent calculations, make sure to base your calculation on the rounded values you enter into WebAssign.)

(a) Determine the current in the starter.
133.83 A       -      Webassign said this answer is correct

(b) Determine the current in the dead battery

0.51A            -      I got this answer as wrong, need help with this.

Explanation / Answer

We know that r is in parallel with R and the dead battery. Therefore, the voltage across r is the same as the VR and the voltage of the dead battery.

Vr = Resistance X Current = (0.08) X 133.83 = 10.7064

We therefore have 10.7064 = 10 + VR

VR = 0.7064

VR = Resistance X Current = 1.3 X Current = 0.7064

Current = 0.543 [A]

The current passing through the resistor R is the same current through the dead battery.

If your answer for the first part is correct, than the answer to the second part is 0.543 [A]

Perhaps rounding error, or the initial answer is incorrect. I am too lazy to fully solve this problem.

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