A laboratory centrifuge uses electrical energy to spin a rotor. The useful transfer is to the kinetic energy store of the rotor. All energy that is not transferred usefully is dissipated.
The centrifuge is tested before and after a modification. The total energy supplied during each operating cycle is unchanged.
| Quantity | Value |
|---|---|
| total energy supplied during each cycle | 4.0 kJ |
| useful energy transferred before the modification | 2.6 kJ |
| efficiency after the modification | 80% |
Calculate the percentage decrease in the energy dissipated during each operating cycle following the modification.
100 exam-style questions on Edexcel GCSE Physics 3.2 Dissipation and efficiency, covering 3.2.1 Dissipation of energy, 3.2.2 Reducing unwanted energy transfers, 3.2.3 Efficiency, and 3.2.4 Increasing efficiency. Each one has a worked solution and a mark scheme showing where the marks go.