indonesia 2005

Indonesia 2005

Indian Ocean 2004

Waves

Waves are everywhere in nature – sound waves, visible light waves, earthquakes, water waves, microwaves…

Waves

What do you know about waves?

Longitudinal Waves

In this type of wave, particles vibrate back and forwards along the direction the wave is

travelling.

Transverse Waves

This type of wave moves perpendicular to the motion of the particle

Standing Waves

Maybe you've noticed or maybe you haven't. Sometimes when you vibrate a string, or cord, or chain, or cable it's possible to get it to vibrate in a manner such that you're generating a wave, but the wave doesn't propagate. It just sits there vibrating up and down in place. These are called standing waves. 

These specialized waves have places where the medium does not vibrate at all, called nodes, and other places where the medium vibrates the most, called antinodes. Standing waves have a changing numbers of nodes and antinodes.

Properties of WavesWhat is meant by the axis of a wave?

The axis is the line runningthrough the middle of thewave pattern.

What is meant by the crest of the wave?

The crest is the top part of the wave

…and the trough?

The trough is the bottompart of the wave.

What is the amplitude of the wave?

The amplitude is thedistance from the axis tothe crest

or from axis to trough.

Definition of Wavelength?The wavelength is thedistance after which thewave pattern repeats itself– the distance between twoidentical points on the wave

Wavelength is given

the symbol λ pronounced lambda.

FrequencyThe frequency of the wave is the

number of waves each second.

It is measured in hertz (Hz) which justmeans “per second”.

Period

The period of a wave is the time takenfor one complete wave to pass a point.

It is measured in seconds (s).

Frequency

The link between the frequency andperiod of a wave

Tf 1

Period

Rearrange to find period

T= nn=cycles f

Draw a WavePosition/Amplitude = 6cmPeriod = 2s

Position/Amplitude = 5cmPeriod = 6s

Position/Amplitude = 12cmPeriod = 10s

Position/Amplitude = 4cmPeriod = 8s