EM Spectrum Tour
Radio to gamma — take the tour of all seven electromagnetic regions. Learn the order, what each one is used for, and which ones are dangerous enough to damage your cells.
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EM Spectrum Tour 🌈
Visible light is just the sliver your eyes can see. It is one small part of the **electromagnetic (EM) spectrum** — a continuous family of transverse waves that all travel at the **same speed through a vacuum** (300,000,000 m/s). On this tour you will meet all seven regions, what each is used for, and which ones can hurt you.
Seven regions 📡
The EM spectrum is grouped into **seven regions**. From longest wavelength to shortest: **radio → microwave → infrared → visible → ultraviolet → X-ray → gamma** They are ALL transverse and ALL travel at the same speed in a vacuum. What changes across the spectrum is the **wavelength**, **frequency** and **energy**.
Order the spectrum
An interactive activity.
The trade-off 📉
As you move from radio towards gamma: • **wavelength gets SHORTER** • **frequency gets HIGHER** • **energy gets HIGHER** So gamma rays have the shortest wavelength, the highest frequency and carry the most energy — which is exactly why the gamma end is the most dangerous.
Most energetic
Which region of the EM spectrum has the HIGHEST frequency and carries the MOST energy?
- Gamma rays
- Radio waves
- Visible light
- Microwaves
Every region has a job 🛰️
Each region is used for different things: • **Radio** — TV and radio broadcasting • **Microwave** — satellite communications and cooking • **Infrared** — electrical heaters, cooking and thermal-imaging cameras • **Visible** — fibre-optic communications (and seeing!) • **Ultraviolet** — security marking and tanning • **X-ray** — medical imaging of bones • **Gamma** — sterilising equipment and treating cancer
Match each region to its use
- Radio waves
- Microwaves
- Infrared
- X-rays
- Gamma rays
- Television and radio broadcasting
- Satellite communications
- Thermal-imaging cameras
- Medical imaging of bones
- Sterilising surgical equipment
Find it on the band
An interactive activity.
The dangerous end ☢️
The three highest-energy regions carry enough energy to knock electrons off atoms — they are **ionising**. Ionising radiation can damage cells and DNA, causing mutations and cancer. The ionising regions are **ultraviolet**, **X-rays** and **gamma rays**. Radio, microwave, infrared and visible light are NOT ionising — they carry too little energy.
Which are ionising?
Select ALL THREE regions of the EM spectrum that are ionising and can damage living cells.
- Ultraviolet
- X-rays
- Gamma rays
- Radio waves
- Microwaves
- Visible light
Not just ionising 🔥
Lower-energy waves can still be harmful in a different way: they **heat** the tissue that absorbs them. Microwaves are absorbed by water in your cells and can heat internal tissue; too much infrared causes skin burns. These are HEATING effects, not ionising ones.
Why the caution?
Radiographers stand behind a screen when taking X-rays. Why are X-rays a health risk?
- They are ionising and can damage cells and DNA
- They cook the body like a microwave oven
- They are extremely loud
- They travel slowly and build up
Reflected, absorbed or transmitted 🪞
When an EM wave meets a surface it can be **reflected**, **absorbed** or **transmitted** — and different substances do different things to different wavelengths. A mirror reflects visible light; black tarmac absorbs it and heats up; glass transmits it. That selective behaviour is how coloured filters and coloured objects work.
Tour summary
The EM spectrum runs from radio to _____. As you move towards gamma the wavelength gets shorter and the frequency and _____ get higher. All EM waves are transverse and travel at the same _____ in a vacuum. The ionising regions — ultraviolet, X-rays and gamma — can damage living _____.