Physics (AS & A Level) · May / June 2017 · Paper 13 · Question 15

A steam turbine is used to drive a generator. The input power to the turbine is $P_I$ and the output power is $P_O$. The power loss in the turbine is $P_L$, as shown below. [diagram: input power $P_I$ → turbine → output power $P_O$ → generator; power loss $P_L$ downward from turbine] What is the efficiency of the turbine?

1. A$\dfrac{P_L}{P_O}$
2. B$\dfrac{P_I}{P_O}$
3. C$\dfrac{P_L}{P_I}$
4. D$\dfrac{P_O}{P_I}$

As printed in the paper