A capacitor has a potential difference of $6.0 \mathrm{V}$ across its plates and stores $9.0 \mathrm{mJ}$ of energy. Which row in the table gives the capacitance of the capacitor and the charge on its plates?

	Capacitance / µF	Charge / mC
A	500	3.0
B	500	18
C	3000	3.0
D	3000	18

 

A capacitor in an electronic circuit is designed to slowly discharge through an indicator lamp. It is decided that the time taken for the capacitor to discharge needs to be increased. Four changes are suggested:

(1) Connect a second capacitor in parallel with the original capacitor.

(2) Connect a second capacitor in series with the original capacitor.

(3) Connect a resistor in parallel with the lamp.

(4) Connect a resistor in series with the lamp.

Which suggestions would lead to the discharge time being increased?

Given a $5000\mu \mathrm{F}$ capacitor has a p.d. of $24 \mathrm{V}$ across its plates.Calculate the energy stored on the capacitor.

Given a $5000\mu \mathrm{F}$ capacitor has a p.d. of $24 \mathrm{V}$ across its plates.The capacitor is briefly connected across a bulb and half the charge flows off the capacitor. Calculate the energy dissipated in the lamp.