How and why are waves transferred in the

manner that they are?

That is to say, “How does a wave get from Point ‘A’ to

Point ‘B’?”

A wave can move along a string because the string is continuous.

• By continuous we mean it is connected to itself.– It is not broken into parts

• If we were to break the string at any point, the wave would, could not, spread across the break.

• The wave can spread through the connection.– Whenever you have an extended body that is all

connected to itself, you can have waves.• The oceans for example, are all connected,

therefore if you were to do a cannonball on the East Coast of the U.S., the wave in theory could travel all the way across the ocean.– This is how Tidal Waves affect areas thousands of

miles away from where they originated.

You’ll get to see more about tidal waves in a later presentation!

• As a wave moves along they carry “Oscillations” along with them.– An Oscillation is the oval shaped pattern of waves

that travel outwards from the source of the wave.• If you have ever dropped an object into the water, the pattern

of rings around the point of entry is the source of the wave.– An earthquake’s epicenter, or source, is also the

source of the powerful shock waves that race outwards in a 360 degree arc.

– Radio and T.V. stations transmit their signal in a 360 degree arc around their transmitter.

• So as you can see all waves move from a central point outwards in a 360 degree arc.

This is what I mean by the “Arc.”

Back to how waves show Oscillations.

• There are two different ways for waves to show oscillations.

• This can be shown as Transverse or Longitudinal waves.

• The difference between the waves is in the way that the material in question moves with respect to the motion of the wave itself.– What that means is that normally when you think of a

wave moving you think of it moving forward like a caterpillar.

• Transverse and Longitudinal waves add an additional degree of motion to this.

Transverse Waves

• A transverse wave has its oscillations perpendicular to the direction of the wave.– The wave moves forward.– The oscillation is up and down.

• The waves that you see in the water are transverse waves.– This is because of the fact that the up and

down motion of the wave is perpendicular to the motion of the wave.

This is what a Transverse Wave looks like.

Longitudinal Waves

• A longitudinal wave has oscillations in the same direction, or parallel, as the wave moves.– If you stretch and relax a phone cord while you are on

the phone and think of the twists in the cord as waves,

– The stretching and relaxing of the cord would represent a longitudinal wave.

• Earthquake wave could be thought of as longitudinal waves due to fact that they are moving in a forward direction, and as they move they compress and relax the materials that they are moving through.

This is what Longitudinal Waves look like.

Look at this and see if you now understand the difference between the two different types of waves.

• Transverse and Longitudinal Waves