Capacitors - exam practice

The initial potential difference across a capacitor is V₀. The capacitor discharges through a circuit of time constant T. The base of natural logarithms is e.

What is the potential difference across the capacitor after time T?

An uncharged capacitor is connected to a power supply which supplies a constant current of 10 μA.

After 100 ms, the potential difference across the capacitor is 5.0 kV.

What is the capacitance of the capacitor?

A 10 μF capacitor stores 4.5 mJ of energy.

It then discharges through a 25 Ω resistor.

What is the maximum current during the discharge of the capacitor?

A parallel-plate capacitor is fully charged and then disconnected from the power supply.

A dielectric is then inserted between the plates.

Which row correctly identifies the charge on the plates and the electric field strength between the plates?

A capacitor of capacitance C has a charge of Q stored on the plates. The potential difference between the plates is doubled.

What is the change in the energy stored by the capacitor?

A capacitor consists of two parallel square plates of side l separated by distance d.

The capacitance of the arrangement is C.

What is the capacitance of a capacitor with square plates of side 2l separated by a distance $\frac{d}{2}$?

A capacitor of capacitance 120 µF is charged and then discharged through a 20 kΩ resistor.

What fraction of the original charge remains on the capacitor 4.8 s after the discharge begins?

Which of the following statements about a parallel plate capacitor is incorrect?

A 1.0 µF capacitor is charged for 20 s using a constant current of 10 µA.

What is the energy transferred to the capacitor?

A 1.0 µF capacitor initially stores 15 µC of charge. It then discharges through a 25 Ω resistor.

What is the maximum current during the discharge of the capacitor?