AP Physics 1 Question 297: Answer and Explanation

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Question: 297

5. Question below refers to the below circuit diagram.

If switch S1 is connected to point A but switch S2 is left unconnected, what is the current through the 1-Ω resistor?

  • A. 0 A
  • B. 2 A
  • C. 3 A
  • D.

Correct Answer: B

Explanation:

B

For Questions 15-17, or any problem that involves an electric circuit with switches, the key is to remember that electricity flows through a closed switch but not an open one. Redraw the circuit, including only the parts that form a closed circuit.

With S1 closed but S2 open, only the left-hand loop is connected. The resistors are in series, so the equivalent resistance is Req = 2 Ω + 1 Ω + 3 Ω = 6 Ω. The current through the circuits including the 1 Ω resistor is Ileft = .