A2L Item 219

Goal: Reason regarding capacitors

Source: 283-545 Adding capacitors in parallel

A capacitor having, C1, is connected to a battery until
charged, then disconnected from the battery. A second capacitor,
C2, is connected in parallel to the first capacitor. Which
statements below are true?

  1. Charge on C1 decreases.
  2. Total charge on C1 and C2 is the same as the original Q.
  3. The total energy stored in both capacitors is the same as the
    original U stored in C1.
  4. The potential (Voltage) across C1 decreases.
  5. All of the above.
  6. Only 1, 2, and 3 are true.
  7. Only 1, 2, and 4 are true.



(7) Statement #3 is the hardest for students to reason about. This is
most easily decided as incorrect if the two capacitors are taken as