Introducing Waves

A wave is a continuous transfer of energy from one place to another. The energy can be in a variety of different forms. You can have waves on the sea which transfer kinetic (movement) energy. The waves that split into different colours carry light energy. And the waves that cause our ear drum to vibrate carry sound energy.

Many of these waves are caused by particles passing energy from one to the other. Think of a Mexican Wave at a football match. The wave travels around the whole stadium - yet the individual particles (the people in this case) only move up or down. They don't move around the stadium as well.

It is important to remember that all waves work in a similar way to this.

Waves Everywhere

The more you think about it the more you realise just how much waves are a part of the world around us.

Take a look at the picture taken from one of the fantastic beaches in Pembrokeshire. It's a winter day, it's cold and windy (and still some people go in to surf!) yet there are many different types of wave in evidence from the picture:

• The sea. OK, that's the obvious one. The sea itself is moving in such a way that the water is forming into waves. Those waves, which might have been quite gentle out at sea, are collapsing into surf as the water becomes more shallow (shallower than the height of the wave).
• Sound. You can probably imagine the noise. The waves crashing will make a sound; the seagulls will be as noisy as usual and there may even be the occaisional shout of encouragement from the surfers. All this noise will reach your ears in the form of sound waves.
• Light. To take the picture light waves bounced off the sea and the surfers and passed through the lens and into the photo-sensitive part of the digital camera. The light waves are slightly different to eac other so the camera interprets them as different colours. The light has also done two special things that waves are able to do. It was reflected (bounced off) the white foam of the surf; and it was refracted (passed through) the clouds in the sky.

Types of Wave

There are two main types of wave, which we will look at in detail later. They are called tranverse waves and longitudinal waves. To describe it simply, the transverse waves are the ones that many people think of first. They are the ones that are caused by the particles moving up and down next to each other. So the wave looks like the waves on the sea.
A longitudinal wave, on the other hand, is caused by its particles moving from side to side next to each other. An example of this is the movement caused along a long, loose spring (like the one in the photograph) when one end is moved in and out.