SAT Subject Physics Practice Question 86: Answer and Explanation

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Question: 86

4. A battery whose emf is 40 V has an internal resistance of 5 Ω. If this battery is connected to a 15 Ω resistor R, what will be the voltage drop across R ?

A. 10 V
B. 30 V
C. 40 V
D. 50 V
E. 70 V

Correct Answer: B

Explanation:

The current through the circuit is

Therefore, the voltage drop across R is V = IR = (2 A)(15 Ω) = 30 V.

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