Properties of Waves
Get to grips with Properties of Waves for GCSE Physics with this free worksheet and full mark scheme — Foundation and Higher exam-style questions with worked answers for AQA, Edexcel and OCR. Waves have a wavelength, frequency, amplitude and period, and the wave speed is given by v = fλ.
Free downloads
These worksheets and mark schemes are original, written for Virtus Academy and checked against the current AQA, Edexcel and OCR specifications. Every worksheet comes with a full mark scheme.
Topic overview
Waves are described by four quantities: amplitude, wavelength, frequency and period.
Amplitude is the maximum displacement of a point on the wave from its undisturbed position — measured from the middle to a peak, not from peak to trough. Wavelength is the distance from a point on one wave to the equivalent point on the next.
Frequency is the number of waves passing a point per second, measured in hertz. Period is the time for one complete wave to pass, and period = 1 ÷ frequency. The wave equation links these: wave speed = frequency × wavelength.
Revision notes
Amplitude and wavelength
Amplitude is the maximum displacement of a point on the wave from its undisturbed position.
It is measured from the middle line to a peak, not from peak to trough — that distance is twice the amplitude. Wavelength is the distance from a point on one wave to the equivalent point on the next.
Frequency and period
Frequency is the number of waves passing a point each second, measured in hertz.
Period is the time for one complete wave to pass a point, in seconds. They are reciprocals: period = 1 ÷ frequency.
The wave equation
Wave speed = frequency × wavelength, v = fλ.
Speed in metres per second, frequency in hertz, wavelength in metres. Wave speed is the speed at which the energy is transferred through the medium.
Key points
- Amplitude is measured from the middle to a peak.
- Wavelength is from one point to the equivalent next point.
- Frequency is waves per second, in hertz.
- Period is the time for one wave, in seconds.
- Period = 1 ÷ frequency.
- Wave speed = frequency × wavelength.
Worked examples
Example 1
A wave has a frequency of 50 Hz and a wavelength of 4 m. Calculate its speed. [2 marks]
Model answer
Wave speed = frequency × wavelength = 50 × 4 (1 mark) = 200 m/s (1 mark).
Example 2
A wave has a frequency of 25 Hz. Calculate its period. [2 marks]
Model answer
Period = 1 ÷ frequency = 1 ÷ 25 (1 mark) = 0.04 s (1 mark).
Example 3
Define amplitude. [2 marks]
Model answer
Amplitude is the maximum displacement of a point on the wave (1 mark) from its undisturbed position (1 mark).
Common mistakes
Measuring amplitude from peak to trough.
That is twice the amplitude. Measure from the middle line to a peak.
Confusing frequency and period.
Frequency is waves per second; period is seconds per wave. They are reciprocals.
Using the wrong units in the wave equation.
Frequency in hertz and wavelength in metres give speed in metres per second.
Saying wavelength is the distance from peak to trough.
It is peak to peak, or any point to the equivalent point on the next wave.
Exam tips
- Measure amplitude from the undisturbed position.
- Remember period and frequency are reciprocals.
- Write the wave equation before substituting.
- Check units before calculating.
Key terms
- Amplitude
- Maximum displacement from the undisturbed position.
- Wavelength
- Distance from a point to the equivalent point on the next wave.
- Frequency
- Waves passing a point per second, in hertz.
- Period
- The time for one complete wave to pass.
Related topics
Written and reviewed against the current AQA, Edexcel and OCR specifications. Spotted an error? Let us know.