Waves & Different Materials
Explain how waves can be absorbed, transmitted, or reflected by different materials, and apply these interactions to explain colour perception, sight, communication technologies, and the effects of different surfaces on wave behaviour
What a learner can do afterwards
- Explains the difference between absorption, transmission, and reflection of waves
- Uses the three interactions to explain how we see coloured objects
- Explains how radio waves, visible light, and infrared are used in different communication technologies
- Describes how the properties of a surface (colour, texture, material) determine how it interacts with radiation
The lesson
You already know that visible light, infrared, and radio waves are all part of the electromagnetic spectrum. When any of these waves reaches a material, one of three things happens: the material absorbs it, transmits it, or reflects it.
A ripe apple looks red because its skin reflects red light back to your eyes and absorbs the other colours in sunlight. If the skin absorbed every colour, including red, the apple would look black instead.
Radio waves pass through walls, so they carry signals for radio, TV, and wifi across a house or city. Visible light travels through glass and thin optical fibres, carrying messages through fibre-optic internet cables. Infrared cannot pass through walls, which is why a remote control only works when you point it at the device.
Dark, rough, matte surfaces absorb more radiation. Light-coloured, smooth, shiny surfaces reflect more. That is one reason mirrors are shiny and silver, while solar panels are usually dark.
Every wave that meets a material is absorbed, transmitted, or reflected, and the colour and texture of the surface decide how much of each happens.
Watch it
Where it sits
This opens up
Nothing builds on it yet.
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.