Efficiency is a measure of how effectively a machine, engine, or process converts input energy into useful output energy or work. It is expressed as a percentage or decimal value between 0 and 1 (or 0% and 100%). A higher efficiency means less energy is wasted as heat, sound, friction, or other unusable forms.

No real machine can achieve 100% efficiency due to the second law of thermodynamics. Some energy is always lost to the environment, primarily as waste heat. Understanding efficiency helps engineers design better systems, reduce energy consumption, and minimize environmental impact.

Efficiency calculations are fundamental in various engineering and scientific fields:

• Power Generation: Evaluating thermal power plants, hydroelectric dams, and renewable energy systems
• Transportation: Comparing fuel efficiency of vehicles and engines
• HVAC Systems: Rating heating and cooling equipment performance
• Manufacturing: Optimizing industrial processes and machinery
• Electronics: Designing power supplies and energy conversion circuits