Question

A capacitor $C$ is charged to a potential difference $V$ and the battery is disconnected. Now, if the capacitor plates are brought closer slowly by some distance

• A. some negative work is done by external agent
• B. External agent does zero work
• C. Work done by external agent can be positive or negative
• D. Some positive work is done by external agent

Answer 1

The correct option is A some negative work is done by external agent

Due to the opposite nature of charges on the two plates, they attract each other.

To bring them closer slowly, the external agent will have to apply force outwards.

As the displacement is inwards, the work done by the external agent will be negative.

Hence, option (c) is the correct answer.