What is a wave?

Wise-up facts about waves

• Waves carry energy from one place to another.
• Because waves carry energy, they can be used for communication (eg radio and television waves) and to transmit signals.
• Waves are vibrations (sometimes you may see these called oscillations) moving from one place to another.
• There are many types of waves. The ones that you need to know about are sound waves, water waves and all the parts of the electromagnetic spectrum.
• For some types of waves, the medium that carries them has to be matter, either solid, liquid or gas. Water waves obviously have to travel in water! Sound waves need a solid, a liquid or a gas to travel in.
• The waves in the electromagnetic spectrum do not need any matter to travel in. As the name suggests, these waves are vibrations of an electrical or a magnetic field.

Question 1

Can you think of an everyday situation that reminds us that electromagnetic waves can travel through a vacuum? (Clue - most of space is a vacuum.)

The Answer

On Earth, we receive light, heat and other radiation from the Sun. These waves have travelled through the vacuum of space for most of their journey.