GCSE Standard Questions: Electricity in the Home

Q13. Light bulbs are labelled with a power input and operating voltage.

(a) Tick the one statement that describes what 'power input' means:

The charge transferred each second by the bulb.
The current through the bulb.
The energy transferred each second to the bulb.
The potential difference across the bulb.

[1 mark]

(b) Write down the equation which links current, potential difference and power.

[1 mark]

(c) A light bulb has a power input of 40 W. The mains potential difference is 230 V. Calculate the current in the light bulb.

[3 marks]

(d) The table below shows information about three different light bulbs.

(i) Write down the equation which links efficiency, total power input and useful power output.

[1 mark]

(ii) Calculate the value of X in the table.

[3 marks]

(e) In addition to power input, light bulbs should also be labelled with the rate at which they emit visible light. Suggest why.

[2 marks]

(Total 11 marks)