Measurements are taken from a parcel conveyor before and after it is serviced. Its efficiency is 0.50 before servicing and 0.80 after servicing. For equal amounts of energy supplied, the unwanted energy transfer after servicing is what percentage of the unwanted energy transfer before servicing?
40%40\%40%
160%160\%160%
30%30\%30%
62.5%62.5\%62.5%
128 exam-style questions on Edexcel GCSE Physics 8.3 Power and efficiency, covering 8.3.1 Power and 8.3.2 Efficiency. Each one has a worked solution and a mark scheme showing where the marks go.