What each part of the spectrum is used for and why, which parts are ionising, radiation dose, how radio waves are made, and the infrared practical.
What you will learn
- Match each group to its uses and say why it suits them
- Explain the risks of ultraviolet, X-rays and gamma rays, and use dose in sieverts
- Carry out and analyse the infrared radiation practical
Each wave, its job
What a wave is used for depends on what absorbs it, what it passes through, and how much energy it carries.
- Radio waves: television and radio broadcasting. They travel long distances and pass through walls.
- Microwaves: satellite communications (they cross the atmosphere easily) and cooking (water in food absorbs them).
- Infrared: grills, toasters and heaters, thermal imaging cameras (warmer things give out more), remote controls.
- Visible light: seeing, photography, signals in optical fibres (thin strands of glass that carry light).
- Ultraviolet: fluorescent lamps, sun beds, security marks that glow on banknotes (special inks absorb ultraviolet and give out visible light).
- X-rays: images of bones (bone absorbs them, soft tissue does not) and airport luggage scanners.
- Gamma rays: sterilising medical instruments and food (they kill microorganisms and pass through the packaging), and treating some cancers.
The rest of this lesson and its 12 practice questions are locked.
In this lesson
- Each wave, its job
- When waves are dangerous
- Required practical: surfaces and infrared
- Try it: Match the use
12 practice questions, marked as you go; about 25 minutes in all.
Key terms
Ionise, Radiation dose
In this unit: Waves and the electromagnetic spectrum
Transverse and longitudinal waves, v = fλ and the wave practicals, reflection and refraction, and the electromagnetic spectrum with its uses, dangers and the infrared practical.
- Transverse and longitudinal waves
- Wave speed and measuring waves
- Reflection and refraction
- The electromagnetic spectrum
- Uses and dangers of electromagnetic waves