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EDEXCEL IGCSE / CERTIFICATE IN PHYSICS

3-1Properties of Waves

- Edexcel IGCSE Physics pages 91 to 98

Content applying to Triple Science only is shown

in red type on the next slide and is indicated on

subsequent slides by TRIPLE ONLY

June 17th 2012

Edexcel Specification

- Section 3 Waves
- b) Properties of Waves
- understand the difference between longitudinal

and transverse waves and describe experiments to

show longitudinal and transverse waves in, for

example, ropes, springs and water - define amplitude, frequency, wavelength and

period of a wave - understand that waves transfer energy and

information without transferring matter - know and use the relationship
- wave speed frequency wavelength v f ?
- use the relationship frequency 1 / time

period f 1 / T - use the above relationships in different contexts

including sound waves and electromagnetic waves - understand that waves can be diffracted when they

pass an edge - understand that waves can be diffracted through

gaps, - and that the extent of diffraction depends on the

wavelength and the physical dimension of the gap.

Red type Triple Science Only

Waves

- A wave is a means of transferring energy and

information from one point to another without

there being any transfer of matter between the

two points.

Transverse Waves

- Transverse waves are waves where the direction of

vibrations is at 90 to the direction in which

the wave travels. - example water waves

Longitudinal Waves

- Longitudinal waves are waves where the vibrations

of the particles are along the direction in which

the wave travels. - example sound waves

Describing Waves1. Amplitude (A)

- Amplitude is the maximum movement of the

particles that make up a wave from their rest

position.

The amplitude is the height of a crest OR the

depth of a trough

2. Wavelength (?)

- Wavelength is the distance between one wave peak

and the next wave peak along the path of a wave. - Wavelength is measured in metres.

Wavelength is also the distance between the

bottom of one trough to the next.

3. Frequency (f )

- Frequency is the number of wave peaks that pass a

point in one second. - Frequency is measured in hertz (Hz)
- 1 Hz 1 peak per second
- 2 Hz 2 peaks per second and so on.
- 1 kilohertz (1kHz) 1 000 Hz
- 1 megahertz (1MHz) 1 000 000 Hz
- 1 gigahertz (1GHz) 1 000 000 000 Hz
- 1 terahertz (1THz) 1 000 000 000 000 Hz

4. Time period (T )

- Time period is the time taken for a source to

produce one wave. - time period 1
- frequency
- and
- frequency 1
- time period

Question 1

- Calculate the frequency of a wave of time period

8.0 seconds. - f 1 / T
- 1 / 8
- frequency 0.125 hertz

Question 2

- Calculate the time period of a wave of frequency

50Hz. - T 1 / f
- 1 / 50
- time period 0.020 second

The wave equation

- speed frequency x wavelength
- v f x ?
- speed in metres per second (m/s)
- wavelength in metres (m)
- frequency in hertz (Hz)
- also f v ?
- and ? v f

v

?

f

Question 1

- Calculate the speed of a water wave of wavelength

3m and frequency 6Hz. - v f x ?
- 6Hz x 3m
- speed 18 m/s

Question 2

- Calculate the frequency of a wave in water of

wavelength 2.0m if its speed is 16m/s. - v f x ?
- becomes
- f v ?
- 16 m/s 2m
- frequency 8 Hz

Question 3

- Calculate the wavelength of a sound wave in water

of frequency 300Hz if its speed is 1500m/s. - v f x ?
- becomes
- ? v f
- 1500 m/s 300 Hz
- wavelength 5 metres

Question 4

- Calculate the speed of a wave that has a

wavelength of 30m and time period 0.04s. - f 1 / T
- 1 / 0.04s
- f 25 hertz
- v f x ?
- 25Hz x 30m
- speed 750 m/s

Complete

Answers

v f ?

15 Hz 4 m

330 m/s 2 m

300 000 000 m/s 1 500 m

300 000 km/s 100 MHz

60 m/s

165 Hz

200 000 Hz

3 m

Diffraction

TRIPLE ONLY

- Diffraction occurs when waves spread out after

passing through a gap or round an obstacle.

TRIPLE ONLY

- Diffraction becomes more significant when the

size of the gap or obstacle is reduced compared

with the wavelength of the wave.

Choose appropriate words to fill in the gaps

below A wave transfers _______ without the

movement of _______ from one place to another.

In a __________ wave the particle ____________

are perpendicular to the direction of wave

travel. Frequency is equal to the number of waves

produced by a source in one _________. Time

period is equal to the ___________ of the

frequency. The speed of a wave in m/s is equal to

its __________ in metres multiplied by its

__________ in hertz.

energy

matter

transverse

vibrations

second

reciprocal

wavelength

frequency

WORD SELECTION

reciprocal

transverse

energy

frequency

wavelength

vibrations

second

matter

Online Simulations

- Simple demonstration of longitudinal transverse

waves - Freezeway.com - Wave lab - shows simple transverse longitudinal

waves with reflection causing a stationary wave -

by eChalk - Wave Effects - PhET - Make waves with a dripping

faucet, audio speaker, or laser! Add a second

source or a pair of slits to create an

interference pattern. Also shows diffraction. - Virtual Ripple Tank - falstad
- Fifty-Fifty Game on Wave Types - by KT -

Microsoft WORD - Simple transverse wave - netfirms
- Simple longitudinal wave - netfirms
- Simple wave comparision - amplitude, wavelength -

7stones - Fifty-Fifty Game on Wave Types - by KT -

Microsoft WORD - Wave on a String - PhET - Watch a string vibrate

in slow motion. Wiggle the end of the string and

make waves, or adjust the frequency and amplitude

of an oscillator. Adjust the damping and tension.

The end can be fixed, loose, or open. - Vend diagram quiz comparing light and sound waves

- eChalk - BBC AQA GCSE Bitesize Revision
- What are waves
- Amplitude, wavelength and frequency
- Wave speed

Properties of WavesNotes questions from pages 91

to 98

TRIPLE ONLY

- (a) What is a wave? (b) Explain the difference

between a transverse and longitudinal wave (see

pages 91 and 92) - Define what is meant by (a) amplitude (b)

wavelength (c) frequency and (d) time period.

(see pages 92 and 93) - (a) State the wave equation. (b) Calculate the

wavelength of a radio wave of frequency 10MHz,

speed 300 000km/s.(see pages 93 and 94) - (a) What is wave diffraction? (b) Draw diagrams

showing how diffraction is affected by the

wavelength of a wave. (see page 97) - Answer the questions on page 98.
- Verify that you can do all of the items listed in

the end of chapter checklist on page 98.

Properties of WavesNotes questions from pages 91

to 98

DOUBLE ONLY

- (a) What is a wave? (b) Explain the difference

between a transverse and longitudinal wave (see

pages 91 and 92) - Define what is meant by (a) amplitude (b)

wavelength (c) frequency and (d) time period.

(see pages 92 and 93) - (a) State the wave equation. (b) Calculate the

wavelength of a radio wave of frequency 10MHz,

speed 300 000km/s. (see pages 93 and 94) - Answer questions 1, 3 and 4 on page 98