Properties of Waves (Edexcel International A Level Physics)

Revision Note

Test Yourself
Lindsay Gilmour



Properties of Waves

  • Waves are generated by oscillating sources 
    • These oscillations travel away from the source

  • Oscillations can propagate through a medium (e.g. air, water) or in a vacuum (i.e. no particles), depending on the wave type

Wave Features

  • In order to describe the properties of travelling waves, the following keywords need to be defined:
    • Wavelength λ (m) is the distance between a point on a wave and the same point on the next cycle of the wave, e.g. two crests, or two troughs
    • Amplitude A (m) is the magnitude of the maximum displacement reached by an oscillation in the wave 
    • Period T (s) is the time taken for one complete oscillation at one point on the wave
    • Frequency f (Hz) is the number of complete wave cycles per second 
    • Wave speed c (m s-1) is the rate of movement of the wave

amplitude-&-wavelength, IGCSE & GCSE Physics revision notes

Diagram showing the amplitude and wavelength of a transverse wave

  • The frequency f and the period T of a travelling wave are related to each other by the equation

Frequency-period equation, downloadable AS & A Level Physics revision notes

Worked example

The graph below shows a travelling wave.


(i) The amplitude A of the wave in metres (m)

(ii) The frequency f of the wave in hertz (Hz)

(i) Identify the amplitude A of the wave on the graph 

    • The amplitude is defined as the maximum displacement from the equilibrium position (x = 0)
    • The amplitude must be converted from centimetres (cm) into metres (m)

A = 0.1 m

(ii) Calculate the frequency of the wave

Step 1: Identify the period T of the wave on the graph 

    • The period is defined as the time taken for one complete oscillation to occur


    • The period must be converted from milliseconds (ms) into seconds (s)

T = 1 × 10–3 s

Step 2: Write down the relationship between the frequency f and the period

f = 1 over T

Step 3: Substitute the value of the period determined in Step 1

f = fraction numerator 1 over denominator 1 cross times 10 to the power of negative 3 end exponent end fraction

f = 1000 Hz

Exam Tip

Every question about waves uses the vocabulary on this page. Many questions start by asking you to define one of them.

So your job is to learn the definitions to the point where you have them memorised.

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Lindsay Gilmour

Author: Lindsay Gilmour

Lindsay graduated with First Class Honours from the University of Greenwich and earned her Science Communication MSc at Imperial College London. Now with many years’ experience as a Head of Physics and Examiner for A Level and IGCSE Physics (and Biology!), her love of communicating, educating and Physics has brought her to Save My Exams where she hopes to help as many students as possible on their next steps.

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