A2L Item 218

• Description: Identify the changes in the charge, potential and stored energy when a charged isolated capacitor is connected to another capacitor.
• Goal: Reason regarding capacitors
• Source: 283-540 Adding capacitors in series
• Keywords: Capacitors, Electromagnetism, Energy, Voltage

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The question for students:

A capacitor, C₁, is connected to a battery until charged, and then disconnected from the battery. A second capacitor, C₂, is connected in series to the first capacitor. What changes occur in capacitor C₁ after C₂ is connected as shown?

1. V same, Q increases, U increases
2. V same, Q decreases, U same
3. V increases, Q decreases, U increases
4. V decreases, Q same, U decreases
5. None of the above
6. Cannot be determined

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Commentary for teachers:

Answer

(5) All quantities remain the same. Some students may consider the capacitors to be connected in parallel despite the figure.

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