Question

Define efficiency.

Answer 1

Efficiency:

1. Efficiency $\left(\eta \right)$ is defined as the ratio of work done $\left(W_{\text{output}}\right)$ by the machine to work done $\left(W_{\text{input}}\right)$ on the machine.
2. It is expressed as $\eta =\frac{\text{Work done on the load}}{\text{Work done by the effort}}=\frac{W_{\text{output}}}{W_{\text{input}}}$.
3. But efficiency is usually expressed in percentage, so we may write $\eta =\frac{W_{\text{output}}}{W_{\text{input}}}\times 100\%$.