Long Red Waves, Short Blue Waves

Open to everyone until Thursday, October 1

To keep it, print it while it is open.

Light is an electromagnetic wave, and every colour has its own wavelength. Red light spreads over a longer wavelength, while blue and violet pack into a shorter one.

In the picture

The gap between two red crests: one long wavelength
The gap between two blue-violet crests: one short wavelength
A crest of the red wave: the high point of a long, stretched cycle
A crest of the blue-violet wave: a high point in a tightly packed cycle

Examples

Sunlight spread by a prism into a rainbow, red at one end and violet at the other
A red tail light and a blue LED glowing side by side

Key takeaways

Wavelength sets the colour: long waves look red, short waves look blue or violet
In a vacuum all colours travel at the same speed, so shorter wavelengths complete more cycles each second