SAT Subject Physics Practice Question 522: Answer and Explanation
C1 is an uncharged capacitor (shown in the circuit above). At t = 0 the switch (SW1) is closed, and C1 begins to charge.
What does graph D show?
A. The value of the current in the circuit as time passes.
B. The value of the voltage across the terminals as time passes.
C. The total value of the resistance as time passes.
D. The total value of the capacitance as time passes.
E. None of the above.
Correct Answer: A
The correct answer is (A). Current flows in the circuit when the switch is first closed. As time passes and the charge builds on the capacitor, the current flow decreases inversely in relation to the charge on the capacitor. When the capacitor is fully charged, the capacitor blocks the circuit as if it was an open and no current is able to flow.