An electric kettle is used to heat water. The kettle transfers 360 000 J of energy from the mains supply. Of this energy, 306 000 J is transferred usefully to the water.
The energy that is not transferred usefully is dissipated. Describe what happens to this energy.
Calculate the efficiency of the kettle.
The hot kettle is stood on a metal surface and the surface becomes warm. Explain why less energy is transferred to the surface when the kettle is stood on a thick plastic mat.
40 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.