Question

A capacitor of capacitance C is charged to a potential difference V from a cell and then disconnected from it. A charge +Q is now given to its positive plate. The potential difference across the capacitor is now

• A. V
• B.
• C.
• D. if V < CV

Answer 1

Answer: (C)

Answer 2

In the figure given below, left X and Y be positive and negative plates. After charging from the cell, the inner faces of X and Y have charges $( q - C V )$ for Y, as shown in (2). Now, the outer faces must have equal charges.

∴ $\mathrm { Q } + \mathrm { CV } - \mathrm { q } = \mathrm { q } - \mathrm { CV }$

or $2 q = 2 C V + Q$

or

Potential difference