The wave equation | Combined science | Quizalize & Oak National Academy

Starter quiz

The figure shows the displacement-time graph for a wave. Which of these correctly describe the features of this wave?

A is the wave period.

A is the wavelength. ✓

B is the wavelength.

B is the amplitude. ✓

C is the amplitude.
A student wants to measure the speed of a wave in a spring. Which quantities do they need to measure to calculate the speed?

The amplitude of the wave.

The distance the wave travels. ✓

The wavelength of the wave.

The time the wave travels for. ✓

The direction of the wave.
Waves can be produced in a rope by shaking one end up and down. Match the changes to their effects on the wave in the rope.

to increase the amplitude

⇔

shake the end up and down a greater distance ✓

to decrease the amplitude

⇔

shake the end up and down a smaller distance ✓

to increase the frequency

⇔

shake the end up and down more times each second ✓

to decrease the frequency

⇔

shake the end up and down less times each second ✓
An oscilloscope and microphone are used to display the waveform for a sound wave. What will happen to the waveform if the frequency of the sound wave is increased?

The wave peaks will be closer together. ✓

The wave peaks will be further apart.

The waves will be less tall.

The waves will be taller.

The wave shape will not change.
On a pond, a ripple travels 0.30 m in 0.40 s. What is the speed of the wave?

1.2 m/s

1.0 m/s

0.75 m/s ✓

4.3 m/s
Sound waves travel at 330 m/s in air. How long will it take a sound wave to travel 5.0 km?

0.15 s

6.6 s

15 s ✓

66 s

150 s

Exit quiz

Which of these does the speed of a wave moving through a medium depend on?

The amplitude of the wave.

The wavelength of the wave.

The wave medium. ✓

The period of the wave.

The frequency of the wave.
Match the wave quantity to the correct symbol.

frequency

⇔

f in Hz ✓

wavelength

⇔

λ in m ✓

period of a wave

⇔

T in s ✓

wave speed

⇔

v in m/s ✓
Which of these is the correct relationship between wave speed, wavelength, and frequency?

wave speed = frequency + wavelength

wave speed = frequency - wavelength

wave speed = frequency × wavelength ✓

wave speed = frequency ÷ wavelength
A loudspeaker produces a series of sound waves of different frequencies. Starting with the longest wavelength, put the waves into order of wavelength.

1

⇔

50 Hz

2

⇔

100 Hz

3

⇔

250 Hz

4

⇔

1.0 kHz

5

⇔

50 kHz
An earthquake produces a wave of wavelength 300 m with a frequency of 6.0 Hz. Calculate the wave speed.

50 m/s

36 m/s

294 m/s

1.8 km/s ✓

50 km/s
Starting with the fastest wave, put the waves in order of decreasing wave speed.

1

⇔

wavelength 0.01 m, frequency 100 000 Hz

2

⇔

wavelength 2.5 m, frequency 60 Hz

3

⇔

wavelength 350 m, frequency 0.1 Hz

4

⇔

wavelength 6.0 cm, frequency 7.0 Hz

Worksheet

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Lesson Details

Key learning points

The speed of a wave depends on the medium it is travelling through
The speed of a wave does not depend on its frequency
For a given wave speed, the higher the frequency, the shorter the wavelength
For a given wave speed, the longer the wavelength, the lower the frequency
Wave speed = frequency x wavelength

Common misconception

In, v = f x λ, speed is dependent on frequency and wavelength, rather than the medium.

Focus on speed being property of a medium and equation not being as an equation with three interdependent variables.

Keywords

Wave equation - wave speed = frequency × wavelength (v = f x λ)
Wave speed - the speed of a wave in a particular medium (material)
Frequency - the number of waves produced each second. Frequency is measured in Hertz (Hz)
Wavelength - the distance between one wave crest (or trough) and the next
Lambda - (λ) the symbol used for the wavelength of a wave