Basic Concepts
In a nutshell: Waves carry energy, and light is a special wave that lets us see the world.
## What Are Waves?
Waves are ways that energy moves through space. There are two main types:
- **Mechanical waves:** Need something to travel through (like sound in air).
- **Electromagnetic waves:** Travel through empty space (like light).
## Light: The Fastest Traveler
Light is an electromagnetic wave. It travels incredibly fast—about 300,000 kilometers per second! Light lets us see, warms the Earth, and helps plants grow.
## How Waves Behave
Waves can reflect (bounce), refract (bend), and interfere (combine with other waves). These behaviors explain rainbows, echoes, and how glasses help us see better.
## Fun with Sound
Sound waves are mechanical waves—when you pluck a guitar string, the vibration travels through the air to your ears.
Examples
- You hear music because sound waves travel through the air.
- Sunlight passing through water creates a rainbow.
Key terms
- Wave
- A disturbance that transfers energy from place to place.
- Electromagnetic Wave
- A wave, like light, that can travel through empty space.
- Reflection
- When a wave bounces off a surface.