Practice question · Multiple choice
A charged parallel-plate capacitor is disconnected from the battery. You pull the plates farther apart. What happens to the voltage between them?
Hints
- Disconnected plates trap their charge. For large plates, the field depends only on the charge density, not on the gap.
- : constant , growing . You also do work against the plates’ attraction, where does that work go?
Show the answer
A. It increases, same field over a larger gap
Why
With trapped, stays fixed, so grows with the gap. The work of pulling the plates apart is stored as extra field energy, you can literally raise a voltage with your bare hands.
Practise Electric Potential and Capacitance
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