AQA GCSE Physics

Revision Notes

6.1.3 The Wave Equation

The Wave Equation

  • Wave speed is defined as:

The distance travelled by a wave each second

  • Wave speed is given the symbol ν and is measured in metres per second (m/s)
  • Wave speed is the speed at which energy is transferred through a medium
  • Transverse and longitudinal waves both obey the wave equation:

Wave equation, IGCSE & GCSE Physics revision notes

  • Where:
    • v = wave speed in metres per second (m/s)
    • f = frequency in Hertz (Hz)
    • λ = wavelength in metres (m)
  • The wave speed equation may need to be rearranged, which can be done using this formula triangle:

Wave speed triangle (2), IGCSE & GCSE Physics revision notes

Worked Example

A wave in a pond has a speed of 0.15 m/s and a time period of 2 seconds.

Calculate:

a) The frequency of the wave

b) The wavelength of the wave

Part (a)

Step 1: List the known quantities

    • Time period, T = 2 s

Step 2: Write out the equation relating time period and frequency

Time Period Equation

Step 3: Rearrange for frequency, f, and calculate the answer

f = 1 ÷ T = 1 ÷ 2

Frequency, f = 0.5 Hz

Part (b)

Step 1: List the known quantities

    • Wave speed, v = 0.15 m/s
    • Frequency, f = 0.5 Hz

Step 2: Write out the wave speed equation

v = f × λ

Step 3: Rearrange the equation to calculate the wavelength

λ = v ÷ f

Step 4: Use the frequency you calculated in part (a) and put the values into the equation

λ = 0.15 ÷ 0.5

Wavelength, λ = 0.30 m

Exam Tip

When stating equations make sure you use the right letters:
For example, use λ for wavelength, not L or W

If you can’t remember the correct letters, then just state the word equations

Be careful with units: wavelength is usually measured in metres and speed in m/s, but if the wavelength is given in cm you might have to give the speed in cm/s

Likewise, watch out for frequency given in kHz: 1 kHz = 1000 Hz

Author: Katie

Katie has always been passionate about the sciences, and completed a degree in Astrophysics at Sheffield University. She decided that she wanted to inspire other young people, so moved to Bristol to complete a PGCE in Secondary Science. She particularly loves creating fun and absorbing materials to help students achieve their exam potential.
Close

Join Save My Exams

Download all our Revision Notes as PDFs

Try a Free Sample of our revision notes as a printable PDF.

Join Now
Already a member?
Go to Top