A 7.0-Ω resistor is connected across the terminals of a battery having an internal emf of 10 V.If there is a 0.50-A current through the circuit,what is the internal resistance of the battery?
A)13 Ω
B)20 Ω
C)10.8 Ω
D)27.0 Ω

Question

Quizplus · Accepted Answer

The total voltage drop across the circuit is 10 V, and the current is 0.50 A. Using Ohm's Law (V = IR), the total resistance is V/I = 10V/0.5A = 20 Ω. The internal resistance is the total resistance minus the external resistance: 20 Ω - 7 Ω = 13 Ω.

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