A device receives 2.0 kJ. A student measures 1.6 kJ of useful output and 0.7 kJ of wasted output.
There is no decrease in any energy store within the device.
Which assessment of the results is correct?
The calculated efficiency is 80%80\%80%, and the energy measurements are consistent.
The calculated efficiency is 80%80\%80%, but the energy measurements are inconsistent.
The calculated efficiency is 125%125\%125%, but the energy measurements are inconsistent.
The calculated efficiency is 125%125\%125%, and the energy measurements are consistent.
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.