Albert Teen

YOU ARE LEARNING:

Waves of Information

# Waves of Information

### Waves of Information

Waves are the transfer energy, and can either be mechanical or electromagnetic. They propagate by vibrating about a rest position.

Out of these, which do you think are examples of waves?

The most important thing you need to know about waves, is that they transfer energy. They can also be described as vibrations or oscillations about a rest position.

What do waves transfer?

1

Consider a stretched out slinky being held at both ends. This is its rest position or equilibrium position.

All physical things are at rest unless they get disturbed.

2

Now consider the person holding the left side jerks the slinky towards the right side.

This creates a pulse in the slinky which moves across from left to right.

3

What is the position of the slinky after the pulse has passed through it?

4

Now consider the person holding the slinky begins to move it up and down at a constant pace.

This creates a wave which is simply a periodic pulse (or in other words, a pulse that gets repeated at a constant rate.)

5

The slinky is what we call the medium of the wave.

This means that the wave itself is energy. The slinky is simply the material that is carrying this wave.

Waves travel through a medium. Pick all the options below that you think correctly describe a medium.

Can some waves travel through empty space, or a vacuum?

True or false: "Waves need matter in order to propagate". ("Propagate" means **** "travel through")

1

Consider the motion of the small buoy attached to the fishing rod. Does it move towards the fisherman or simply up and down? Answer up and down OR towards.

2

The buoy moves up and down rather than towards the fisherman.

This shows that the wave is not making the water move towards the fisherman, because matter is not transferred.

3

Here you can see a sound wave moving through a wall.

The sound waves transfer energy through the wall, rather than transmitting the matter that makes up the wall. If sound waves transmitted the matter, the wall would move!

There are 2 types of waves: mechanical waves and electromagnetic waves.

1

Mechanical waves require a physical material to travel through because they vibrate the particles of it. Which one do you think is an example of a mechanical wave? Answer water waves OR light waves.

2

Electromagnetic (EM) waves do not require any particles in order to travel. This means they can travel through a vacuum (empty space). Which one do you think is an example of an electromagnetic wave? Answer sound OR light.

Can mechanical waves (like sound) travel through a vacuum?

Can electromagnetic waves (like light) travel through a vacuum?