A displacement-time graph of a wave is a representation of a wave.
A displacement-time graph of a wave shows how the displacement at one point varies as the wave passes
The distance between two wave crests on a displacement-time graph is equal to the period of the wave
The period of a wave, T, is equal to the time of one complete oscillation
Frequency is equal to 1 / period

Common misconception

A displacement-time graph is a picture of a wave.

Interpret and sketch displacement-time graphs of waves that are compared to descriptions of each wave.

Keywords

Wave medium - the wave medium is the material that a wave can move through.
Displacement - displacement at a point of a wave is the distance that the wave medium is from its rest position.
Period (of a wave) - period (of a wave), T, is the time for a complete wave to pass any point, which is the same as the time to make one complete wave.
Frequency - frequency is the number of waves produced each second. Frequency is measured in Hertz (Hz).

Practice interpreting displacement-time graphs before asking students to sketch them. Focus on reading the axes each time to identify what is represented on each one and the scale. Ask pupils to describe each wave from its graph.

Teacher tip

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

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Starter quiz

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6 Questions

Q1.

How does the ball move as the water wave moves forwards?

Correct answer: up and down

forwards and backwards

forwards with the wave

Q2.

A water wave is an example of a wave.

Correct Answer: transverse, mechanical

Q3.

Is a wave on a rope a transverse wave?

Correct answer: yes, it is a transverse wave

no, it is a longitudinal wave

no, it is a mechanical wave

Q4.

Where is the rest postion of water in this wave?

level with the top of the wave

Correct answer: level with the middle of the wave

level with the bottom of the wave

Q5.

What is the amplitude of a water wave?

the distance between one wave crest and the next

the distance between a crest of a wave and a trough

Correct answer: the distance between a crest of a wave and the rest postion

Q6.

What is the wavelength of a water wave?

Correct answer: the distance between one wave crest and the next

the distance between a crest of a wave and a trough

the distance between a crest of a wave and the rest postion

Exit quiz

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6 Questions

Q1.

What type of graph is often used to represent a wave?

Correct answer: displacement-time graph

distance-speed graph

temperature-time graph

time-velocity graph

Q2.

What is the period of a wave?

the distance between two wave crests

the maximum displacement of the wave from equilibrium

the speed at which the wave moves forwards

Correct answer: the time it takes for one complete oscillation

Q3.

What is the distance between two wave crests on a displacement-time graph equal to?

the amplitude of the wave

the frequency of the wave

Correct answer: the period of the wave

the wavelength of the wave

Q4.

Which statement is true about a displacement-time graph of a wave?

it is a picture of the wave

it represents the wavelength of the wave

Correct answer: it shows the displacement at one point as the wave passes

it shows the frequency of the wave

Q5.

Which equation represents the relationship between frequency and period?

frequency = period x wavelength

frequency = period / wavelength

Correct answer: frequency = 1 / period

frequency = amplitude / period

Q6.

Put these waves in order of frequency, starting with the highest frequency.

1 - four complete oscillations in 6 s

2 - one complete oscillation in 2 s

3 - six complete oscillations in 15 s

4 - three complete oscillations in 9 s