SAT Subject Physics Practice Question 336: Answer and Explanation
32. A 24 V battery is connected to a 4 ohm resistor, causing a current of 5 amperes. What is the internal resistance of the battery?
A. 0 W
B. .8 W
C. .4 W
D. 1.6 W
E. 1.2 W
Correct Answer: B
The correct answer is (B). A voltage of 24 V should yield a current of 6A when it is hooked to a 4Ω resistor. The internal resistance of the battery is found . The extra .8Ω of resistance is the internal resistance of the battery.