Electromagnetic Spectrum

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What Are Electromagnetic Waves?

Electromagnetic waves are a special type of wave that can carry energy from one place to another. Unlike sound waves or water waves (which need a material like air or water to travel through), electromagnetic waves can travel through empty space — a vacuum — as well as through materials.

All electromagnetic waves share three important properties:

1. They are all transverse waves
   This means the vibrations (or oscillations) happen at right angles to the direction the wave is traveling. Imagine shaking a rope up and down — the wave travels along the rope, but the rope itself moves up and down perpendicular to that direction.

2. They can all travel in a vacuum
   A vacuum is empty space with no air, no matter, nothing at all. This is also called free space. Most waves (like sound) cannot travel through a vacuum because they need particles to vibrate. Electromagnetic waves don't need particles — they can travel through completely empty space.

3. They all travel at the same speed in a vacuum
   In free space (or a vacuum), all electromagnetic waves travel at exactly the same speed. This speed is called the speed of light, represented by the letter c.
   Speed of light in a vacuum: c = 3.0 × 10⁸ m/s (that's 300,000,000 meters per second!)

Note: The speed of light in air is approximately the same as in a vacuum, so we usually use the same value.

Because electromagnetic waves are transverse waves, they can be reflected (bounced back), refracted (bent when entering a different material), diffracted (spread out when passing through gaps), and they can also be polarised and create interference patterns.