Efficiency

Definition

Efficiency is a measure of how well energy or work input is converted into useful work output. It is often expressed as a percentage and calculated as the ratio of useful output to total input.

5 Must Know Facts For Your Next Test

1. Efficiency can never exceed 100% due to the conservation of energy and real-world losses such as friction and heat dissipation.
2. The formula for efficiency is $\text{Efficiency} = \left( \frac{\text{Useful Energy Output}}{\text{Total Energy Input}} \right) \times 100$.
3. In physics, efficiency helps determine how effectively a machine or system converts energy from one form to another.
4. Higher efficiency means less energy waste, making systems more sustainable and cost-effective.
5. Common examples include the efficiency of engines, electrical appliances, and renewable energy systems.

Review Questions

• What does an efficiency of 75% indicate about a system's energy conversion?
• Why can efficiency never be greater than 100%?
• How do you calculate the efficiency of a machine if you know its useful output and total input?

Related terms

Work: Work is done when a force applied to an object moves that object in the direction of the force. It is calculated as $W = Fd$, where $F$ is force and $d$ is displacement.

Energy: Energy is the capacity to do work. It exists in various forms such as kinetic, potential, thermal, electrical, chemical, and nuclear.

Conservation of Energy: The principle stating that the total energy in an isolated system remains constant over time. Energy cannot be created or destroyed but only transformed from one form to another.