Two electric drills are compared. Drill R is supplied with 500 J of energy every second and drill S is supplied with 400 J every second. In both drills, 100 J of this energy is dissipated to less useful stores each second. Which statement is correct?
the drills are equally efficient, because each dissipates the same energy each second
drill S is more efficient, because it is supplied with less energy each second
drill R is more efficient, because the energy it dissipates is a smaller proportion of its input
drill S is more efficient, because the energy it dissipates is a greater proportion of its input
104 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.