An electric water heater transfers a total of 3.60×106 J3.60 \times 10^6\text{ J}3.60×106 J of energy during operation. Of this, 3.42×106 J3.42 \times 10^6\text{ J}3.42×106 J is usefully transferred to the water.
Calculate the efficiency of the energy transfer to the water as a proportion.
The power rating of the heater is 2.40 kW2.40\text{ kW}2.40 kW. Calculate the time taken for the heater to output the total 3.60×106 J3.60 \times 10^6\text{ J}3.60×106 J of energy. State the unit.
26 exam-style questions on AQA GCSE Physics 1.2 Conservation and dissipation of energy, covering 1.2.1 Energy transfers in a system and 1.2.2 Efficiency. Each one has a worked solution and a mark scheme showing where the marks go.