New
New
Year 10
OCR
Foundation

# The wave equation

I can describe how the frequency of a wave moving through a particular medium is related to its wavelength.

New
New
Year 10
OCR
Foundation

# The wave equation

I can describe how the frequency of a wave moving through a particular medium is related to its wavelength.

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## Lesson details

### Key learning points

1. The speed of a wave depends on the medium it is travelling through
2. The speed of a wave does not depend on its frequency
3. For a given wave speed, the higher the frequency, the shorter the wavelength
4. For a given wave speed, the longer the wavelength, the lower the frequency
5. 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

Demonstrate the movement of waves in a spring, rope and ripple tank showing that the wave speed (measured using distance and time) is independent of frequency but changes when the medium is altered.
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).

## Starter quiz

### 6 Questions

Q1.
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.
Correct answer: A is the wavelength.
B is the wavelength.
Correct answer: B is the amplitude.
C is the amplitude.
Q2.
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.
Correct answer: The distance the wave travels.
The wavelength of the wave.
Correct answer: The time the wave travels for.
The direction of the wave.
Q3.
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.
Correct Answer:to increase the amplitude,shake the end up and down a greater distance

shake the end up and down a greater distance

Correct Answer:to decrease the amplitude,shake the end up and down a smaller distance

shake the end up and down a smaller distance

Correct Answer:to increase the frequency,shake the end up and down more times each second

shake the end up and down more times each second

Correct Answer:to decrease the frequency,shake the end up and down less times each second

shake the end up and down less times each second

Q4.
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?
Correct answer: 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.
Q5.
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
4.3 m/s
Q6.
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
66 s
150 s

## Exit quiz

### 6 Questions

Q1.
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 period of the wave.
The frequency of the wave.
Q2.
Match the wave quantity to the correct symbol.

f in Hz

λ in m

Correct Answer:period of a wave,T in s

T in s

v in m/s

Q3.
Which of these is the correct relationship between wave speed, wavelength, and frequency?
wave speed = frequency + wavelength
wave speed = frequency - wavelength
Correct answer: wave speed = frequency × wavelength
wave speed = frequency ÷ wavelength
Q4.
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
Q5.
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