# Formula Power Conversion Efficiency of a Machine

## Conversion Efficiency

Unit
Conversion efficiency tells how effectively, for example, a machine can convert one form of energy (e.g. mechanical energy) into another form of energy (e.g. electrical energy). The conversion efficiency can also be calculated by using the energy ratio:$$\eta ~=~ \frac{W_+}{W_-}$$Here $$W_-$$ is the supplied energy and $$W_+$$ is usable energy.

## Power supplied

Unit
Energy supplied to the system per time period $$\Delta t$$.

## Usable power

Unit
Energy gained / released from the system per time period $$\Delta t$$.