Electromagnetic Spectrum

The electromagnetic spectrum orders waves by wavelength, from long radio waves to short gamma rays. All these waves travel at the speed of light in a vacuum and carry energy.

This picture is part of the full library

Every lesson is open to everyone for 7 days after it is published. This one came out on September 15, 2026: its text stays readable here, and its picture opens with a subscription.

The app is free. A subscription opens every lesson, in every school year.

Age 18: open this week

In the picture

Leftmost glass rod with the widest-spaced sine wave
Second glass rod from the left
Fourth glass rod from the left
Rightmost glass rod with the tightest-spaced sine wave

Examples

A radio antenna receiving an FM broadcast
A microwave oven heating food

Key takeaways

Wavelength and frequency are inversely related.
Visible light is a small part of the full spectrum.

Carry on in the app

Three questions on this lesson. It has left the free week, so its quiz is for subscribers.

At least one new illustrated lesson every weekday for your child’s year, with its quiz and a reminder at 6:15 pm.

Free app, optional subscription
App Store Google Play