Properties of waves Cambridge IGCSE Combined Science revision
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In plain words
A wave carries energy from place to place without carrying the stuff it travels through. A Mexican wave goes round a stadium, but everybody stays in their seat. Wave speed is how many waves pass each second, times how long each one is.
Three things to know
- Waves transfer energy without transferring matter. In a transverse wave the vibrations are at right angles to the direction of travel (light, water waves); in a longitudinal wave they are along it (sound).
- Wave speed = frequency × wavelength (v = fλ). Frequency is the number of waves each second, in hertz.
- Waves can be reflected, refracted (change speed and direction) and diffracted (spread out through a gap).
Worked example
A wave has a frequency of 50 Hz and a wavelength of 0.2 m. Find its speed.
- v = f × λ.
- = 50 × 0.2 = 10 m/s.
Tips and tricks
- Transverse: the vibrations are at right angles to the direction of travel (light, water). Longitudinal: they are along it (sound).
- When a wave changes speed, its frequency stays the same. Only the speed and the wavelength change.
It lands in your notebook with its questions as flashcards.
Properties of waves: 6 questions and answers
These are the quiz’s questions. Do the quiz first, then come back here for the ones that got you.
What do waves transfer?
The medium vibrates but does not travel with the wave.
Which is a longitudinal wave?
In sound the air vibrates back and forth along the direction of travel.
A wave has frequency 10 Hz and wavelength 3 m. What is its speed?
v = fλ = 10 × 3.
What is the amplitude of a wave?
It is the height of a crest above the middle line.
What happens to a wave's frequency when it passes from deep to shallow water?
The speed and wavelength change, but the same number of waves arrive each second.
Waves spread out after passing through a narrow gap. What is this called?
Diffraction is the spreading of waves at a gap or edge.
Quiz
6 questions
Tap an answer and you’ll see straight away whether it’s right, and why.
Worksheet
4 questions, 9 marks. Write your answers on paper, then check them.
Properties of waves
Cambridge IGCSE Combined Science 0653 · 9 marks · papermunch.org
Name ______________________________ Date ______________
A wave has a frequency of 5.0 Hz and a wavelength of 0.40 m. Calculate its speed.[2]
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2.0 m/s. 5.0 × 0.40.
Sound travels at 340 m/s in air. Calculate the wavelength of a note of frequency 680 Hz.[3]
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0.50 m. λ = v ÷ f = 340 ÷ 680.
State the difference between a transverse wave and a longitudinal wave.[2]
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In a transverse wave the vibrations are perpendicular to the direction of travel; in a longitudinal wave they are parallel to it.
30 waves pass a point in 12 seconds. Calculate the frequency.[2]
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2.5 Hz. 30 ÷ 12.
Answers: Properties of waves
- 1. 2.0 m/s. 5.0 × 0.40.
- 2. 0.50 m. λ = v ÷ f = 340 ÷ 680.
- 3. In a transverse wave the vibrations are perpendicular to the direction of travel; in a longitudinal wave they are parallel to it.
- 4. 2.5 Hz. 30 ÷ 12.