Physics / core

Efficiency

Also known as: Ξ·

definition

The ratio of useful output energy to total input energy, expressed as a percentage showing how little is wasted. Key to understanding energy use and why we need better technology.

πŸ’‘ Intuition

What fraction of the energy you put in actually goes where you want it to go, rather than being wasted as heat.

Core Idea

Efficiency can never exceed 100%β€”you can't get more out than you put in.

πŸ”¬ Example

A car engine: only ~25% of fuel energy becomes motion; the rest becomes heat.

🎯 Why It Matters

Key to understanding energy use and why we need better technology.

⚠️ Common Confusion

High efficiency doesn't mean low power useβ€”it means less waste.

Related Concepts

Prerequisites

Next Steps

How Efficiency Connects to Other Ideas

To understand efficiency, you should first be comfortable with energy and work. Once you have a solid grasp of efficiency, you can move on to power.

Go Deeper

Frequently Asked Questions

What is Efficiency in Physics?

The ratio of useful output energy to total input energy, expressed as a percentage showing how little is wasted.

Why is Efficiency important?

Key to understanding energy use and why we need better technology.

What do students usually get wrong about Efficiency?

High efficiency doesn't mean low power useβ€”it means less waste.

What should I learn before Efficiency?

Before studying Efficiency, you should understand: energy, work.

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