© Boardworks Ltd 2004 1 of 20 © Boardworks Ltd 2005 1 of 27 Wave Character KS4 Physics

© Boardworks Ltd 20041 of 20 © Boardworks Ltd 20051 of 27

Wave Character

KS4 Physics


Wave Character

Transverse waves

Longitudinal waves

Summary activities

Wave speed

Contents


A transverse wave can be made by vibrating the left hand side of a piece of rope up and down.

If you could freeze the action you would see the wave has the shape shown below.

Energy transferred

Energy is transferred along the rope away from the source of the wave.

Transverse wave character


The parts of a transverse wave are given the names:

Peak

Trough

Parts of a transverse wave


Particle movement in a transverse wave

In a transverse wave each particle of the material moves at right angles [90º] to the direction the energy is moving in:

Par

ticle

m

ovem

ent

Energy movement

Only the energy moves along the wave the particles only move up and down.


Wavelength of transverse waves

Time

Trough

-

Dis

plac

emen

t

+The wavelength of a wave is the length of one wave. This is the distance between two identical points on neighbouring waves. Wavelength is represented by the symbol .


Amplitude of transverse waves

Timea

a

-

Dis

plac

emen

t

+The amplitude of a wave is the maximum displacement of a wave. For a transverse wave, this is the height of a peak or trough from the rest position of the wave (zero displacement).

The larger the amplitude of a wave the more energy it has.


Frequency of transverse waves

The number of waves passing through a point each second is called frequency.

Frequency = number of waves past a point / time

Frequency is measured in hertz (Hz)

1 wave per second = 1 Hz

If the wave below passes a point in 1 second, what is its frequency? 4 Hz


Wave Cycles Time (s)

Freq(Hz)

2

2

2

Frequency activity

Complete the table:

6

10

1

3

5

0.5


Transverse wave simulation


Wave Character

Transverse waves

Longitudinal waves

Summary activities

Wave speed

Contents


A longitudinal wave can be made by vibrating the left hand side of a spring from side to side.

If you could freeze the action you would see the wave has the shape shown below.

Energy transferred

Energy is transferred along the spring away from the source of the wave.

Longitudinal waves


The parts of a longitudinal wave are given the names:

Compression

Rarefaction

Parts of a longitudinal wave


particle movement

energy movement

When you speak to someone, the air vibrates as a longitudinal wave.

In a longitudinal wave each particle of the material moves in the same direction as the direction the energy is moving in.

Particle movement in a longitudinal wave


The wavelength of a wave is the length of one wave. This is distance between two identical points on neighbouring waves. Wavelength is represented by the symbol .

Wavelength of a longitudinal wave


Transverse of longitudinal?

Transverse Longitudinal

sound

p waves

light

s waves

water

ultrasound

ultraviolet

soundlight

water p waves

ultrasound

s waves ultraviolet


Wave Character

Transverse waves

Longitudinal waves

Summary activities

Wave speed

Contents


= 2m

1 second later :

Imagine waves on the sea travelling over a shipwreck:

Wave speed


In the diagram, 5 waves pass the shipwreck in 1 second, so the frequency is 5 Hz.

The wavelength () is 2 m, which means that the waves travel 10 m in 1 s.

The speed is therefore 10 m/s.

So, in this example:

frequency x wavelength = speed

5 Hz x 2 m = 10 m/s

Wave speed


V = x

wave speed = frequency x wavelength

Wave speed is measured in meters per second (ms-1)

Frequency is measured in Hertz (Hz)

Wavelength is measured in metres (m)

Wave speed formula


3) …and you are left with the sum…

f = V ÷

v

f

x

Wave speed formula triangle

Formula triangles help you to rearrange formula. The triangle for the wave formula is shown below.

Cover up whatever quantity you are trying to find, and you will be left with the calculation required.

1) So if you were trying to find frequency (f)…

2) …you would cover up f…


The photograph shows waves travelling across the surface of a pond.

The wavelength is estimated at 0.15m.

1m

If the frequency of the wave is 0.2 Hz, what is the speed of the wave?

wave speed = frequency x wavelength

wave speed = 0.2 x 0.15

wave speed = 0.03 ms-1

Wave speed formula example


Wave F (Hz) (m) V (ms-1)

Water 2 1.5

Mexican 40 8

Musical note

256 339

Rope 3 0.8

Ultrasound 35,000 339

Wave speed questions

1.32

0.2

3

2.4

0.01

Complete the table:


Wave Character

Transverse waves

Longitudinal waves

Summary activities

Wave speed

Contents


Glossary

amplitude – The height of a peak (or trough) of a wave from its rest position.

compression – A stretched-out section of a longitudinal wave.

frequency – The number of waves passing a point each second. It is measured in hertz (Hz).

longitudinal waves – Waves in which the vibrations are backwards and forwards and so move in the direction of travel, e.g. sound and P waves.

rarefaction – A bunched-up section of a longitudinal wave. transverse waves – Waves in which the vibrations are

from side to side and so move at right angles to the direction of travel, e.g. electromagnetic, water and S waves.

wavelength – The distance between two identical pointson neighbouring waves.


Anagrams


Multiple-choice quiz

Documents

© Boardworks Ltd 2004 1 of 20 © Boardworks Ltd 2005 1 of 27 Wave Character KS4 Physics