Power Efficiency

Contents

Key Stage 4

Meaning

Power efficiency is a ratio of useful power transferred to total power put into a system.

About Efficiency

Power efficiency is a measure of how effectively energy is transferred from one energy store into an intended energy store.

Efficiency may be written as a percentage or as a decimal.

Efficiency as a percentage can never be greater than 100% and as a decimal can never be greater than 1 because you can never get more energy out than you put in due to Conservation of Energy.

Equation

Efficiency = (Useful Power Out)/(Total Power In)

\(Efficiency = \frac{P_{Useful}}{P_{Total}}\)