3.2 Efficiency of Energy Conversion Devices
Efficiency is the useful output of energy. To calculate efficiency the following formula can be used:
Example 1
An electric motor consumes 100 watts (a joule per second (J/s)) of power to obtain 90 watts of mechanical power. Determine its efficiency.
Solution:
Input to the electric motor is in the form of electrical energy and the output is mechanical energy.
Using the efficiency equation,
Or efficiency is 90%.
