Efficiency
Also: conversion efficiency, η
The fraction of input energy or power delivered as useful output.
Efficiency is output divided by input for the same boundary and interval; the remainder becomes loss, often heat, sound, or deformation.
- Units
- dimensionless, often percent
- Formula
η = P_out/P_in
Example An 80% gearbox delivering 3 W needs 3.75 W mechanical input.
Common misconception Efficiency cannot exceed 100% for a passive conversion boundary, and it is not constant at every load.