Electricity: Capacitors

Question 1

What will a capacitor of 1 farad store.

Answer 1

A capacitor of 1 farad will store 1 coulomb of charge when the potential difference across it is 1 volt.

Question 2

Draw the current and potential difference with time graphs for a Charging cycles of a Capacitor.

Answer 2

Current = Curve starts at positve y value and cures down to 0
Voltage = Curve starts at 0 and curves up to Supply Voltage.

Question 3

Draw the current and potential difference with time graphs for a Charging cycles of a Capacitor.

Answer 3

Current = Curve starts at negative Y value and curves up to 0
Voltage =Curve starts at positve y value and cures down to 0

Question 4

Effect of Capacitence on charging and discharging curves

Answer 4

If capacitance increases (with the same resistance), the capacitor stores more charge and therefore takes a longer time to charge and discharge. Initial current is unchanged.

Question 5

Effect of resistance on charging and discahring curves.

Answer 5

Increasing the resistance reduces te charging current, so it takes a longer time to charge the capacitor.

Question 6

How do you find the energy in a capacitor from a graph

Answer 6

The energy stored in a capacitor is found from the area under the QV graph.