Physics · Oct / Nov 2025 · Paper 12 · Question 17

What is the definition of efficiency?

1. Aefficiency = \frac{\text{useful energy input}}{\text{total energy output}}
2. Befficiency = \frac{\text{total energy input}}{\text{total energy output}}
3. Cefficiency = \frac{\text{useful energy output}}{\text{total energy input}}
4. Defficiency = \frac{\text{total energy output}}{\text{total energy input}}

As printed in the paper