Electrical current transfers energy around circuits. The power is the rate at which a circuit transfers energy.

How much energy is transferred by a 250 W television set in 4 minutes?

1,000 J

60,000 J

62.5 J

If 25 C of charge shifts 50 J of energy between two points, what is the voltage between those points?

2 V

0.5 V

5 V

What power is transmitted by a current of 2 A in a resistor with a potential difference across it of 5 V?

2.5 W

10 W

0.4 W

What power is transmitted by a current of 2 A in a 6 Ω resistor?

12 W

3 W

24 W

What is the power output of a mains transformer with a current of 0.2 A passing through it?

46 W

1,150 W

The power input into a transformer of 100 per cent efficiency is 2,000 W. What will the power output be?

Less than 2,000 W

2,000 W

More than 2,000 W

The power input of a transformer is 1,200 W and the output voltage is 120 V. What will the output current be?

0.1 A

1 A

10 A

How is electricity transmitted across the UK?

At a high current and a low voltage

At a high current and a high voltage

At a high voltage and a low current

Why is electricity transmitted around the country at 400,000 V?

Electricity is generated at 400,000 V

This reduces the heating effect of the current in the transmission wires

Some large factories need to operate at 400,000 V

If a 6 V cell transfers 36 J of energy around a circuit, how much charge has flowed?

0.16 C

216 C

6 C