DC - Parts 7 & 8 Revision

Energy is stored in a capacitor in the:

• magnetic field within the dielectric

• magnetic field around the capacitor leads

• electric field across the dielectric

• electric field across the entire circuit

Capacitors store an electric charge whose magnitude depends upon the plate area, the type of dielectric and the:

• thickness of the plates

• length of the plates

• distance between the plates

• size of the plates

A capacitor which has been connected to a dc supply for a period of time displays a similar electrical characteristics to that of:

• a closed circuit

• a short circuit

• an open circuit

• an a.c. circuit

Increasing the value of resistance in a series RC circuit will:

• increase the time constant of the circuit

• decrease the time constant of the circuit

• increase the charging current

• minimise the voltage drop across the resistor

Which of the following materials cannot be used as a dielectric?

• air

• paper

• carbon

• oil

• plastic

The principal danger associated with charged capacitors is electric shock. This can be lethal, so capacitors should always be:

• allowed to cool before handling

• avoided at all costs

• discharged before handling

• ignored, as the shock really isn't that bad

• 230µF

• 42.5mF

• 23.53µF

• 23.53F

For the diagram shown, the time constant is:

• 2.21 seconds

• 2.21 minutes

• 47 seconds

• 11 seconds

For the diagram shown, the time constant is 1.5 seconds.

How long will it take to fully charge the capacitor?

• 1.5 seconds

• 1.5 minutes

• 7.5 seconds

• 4.5 seconds

For the diagram shown, what will be the voltage across the capacitor after one time constant?

• 10V

• 3.68V

• 6.32V

• 0V