Year 10 P2

A hairdryer transfers 10,000 J of energy in 4 s. What is its power?

• 40,000 W

• 2,500 W

• 25,000 W

• 5,000 W

How can the thermal store of a house be prevented from dissipating for as long as possible?

• Decrease the thermal conductivity of the walls

• Reduce the insulation in the house

• Keep the heating on its highest setting

Which of these is a renewable energy source?

• Coal

• Nuclear fuel

• Hydro-electric power

A step-up transformer is used to do which of the following?

• Increase the current

• Make the power line wires hot

• Reduce the voltage

• Decrease the current

What is the frequency and voltage of the UK mains electricity?

• 50 Hz and 230 V alternating current

• 50 Hz and 230 V direct current

• 230 Hz and 50 V alternating current

What is the efficiency of Christmas lights that give out 10 J of light radiation for an electrical input of 200 J?

• 0.20

• 0.10

• 0.05

• 0.5