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EDEXCEL IGCSE / CERTIFICATE IN PHYSICS 3-1 Properties of Waves

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## EDEXCEL IGCSE / CERTIFICATE IN PHYSICS 3-1 Properties of Waves

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### EDEXCEL IGCSE / CERTIFICATE IN PHYSICS 3-1Properties of Waves

Content applying to Triple Science only is shown in red type on the next slide and is indicated on subsequent slides by ‘TRIPLE ONLY’

Edexcel IGCSE Physics pages 91 to 98

June 17th 2012

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 × λ

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.

Edexcel SpecificationRed 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.

wave direction

TRANSVERSE WAVE

Transverse WavesTransverse waves are waves where the direction of vibrations is at 90° to the direction in which the wave travels.

example: water waves

wave direction

LONGITUDINAL WAVE

longitudinal wave in slinky

Longitudinal WavesLongitudinal 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.

amplitude

rest position

amplitude

The amplitude is the height of a crest OR the depth of a trough

2. Wavelength (λ)

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

wavelength

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

T = 1 / f

f = 1 / T

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=fxλ

speed in metres per second (m/s)

wavelength in metres (m)

frequency in hertz (Hz)

also:f=v÷λ

and: λ=v÷f

v

f

λ

Question 1

Calculate the speed of a water wave of wavelength 3m and frequency 6Hz.

v=fxλ

= 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=fxλ

becomes:

f=v÷λ

= 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=fxλ

becomes:

λ=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=fxλ

= 25Hz x 30m

speed = 750 m/s

Sea wave diffraction

DiffractionDiffraction occurs when waves spread out after passing through a gap or round an obstacle.

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:

frequency

transverse

reciprocal

energy

second

vibrations

wavelength

matter

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

Online SimulationsProperties of WavesNotes questions from pages 91 to 98

- (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

- (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

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