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

Question

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

Options

G1 Physics · Accepted Answer

After disconnecting the cell, adding +Q to one plate changes the two plate charges asymmetrically. Using the field of two infinite sheets, the potential difference increases by Q/(2C), so V′ = V + Q/(2C). Hence C.