AP Physics 1 Question 171: Answer and Explanation
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The circuits shown in the figure contain the same three resistors connected in different configurations. Which of the following correctly explains which configuration (if either) produces the larger current coming from the battery?
- A. Circuit 1; the larger resistor is closer to the battery.
- B. Circuit 2; the equivalent resistance of the three resistors is smaller than in circuit 1.
- C. Neither; the batteries are both the same.
- D. Neither; the individual resistors are the same in each circuit, even if they are in a different order.
Correct Answer: B
B-The equivalent resistance of the parallel resistors in circuit 1 is 12 kΩ; adding that to the 100 kΩ resistor gives a total resistance in circuit 1 of 112 kΩ. Circuit 2's parallel combination has an equivalent resistance of 23 kΩ, giving a total resistance in that circuit of 43 kΩ. By V = IR applied to both circuits in their entirety with the same total voltage, the circuit with smaller total resistance will produce the larger current. That's circuit 2.