Describing Waves (WJEC GCSE Science (Double Award): Physics): Revision Note

Describing Waves

• When describing wave motion, there are several terms which are important to know, including:

  • amplitude, $A$

  • wavelength, $\lambda$

  • frequency,$f$

  • wave speed, $\nu$ 

Amplitude

• Amplitude is defined as:

  The distance from the undisturbed position to the peak (crest) or trough of a wave

• It is given the symbol $A$ and is measured in metres (m)

• Amplitude is the maximum or minimum displacement from the undisturbed position

Wavelength

• Wavelength is defined as

  The distance from one point on the wave to the same point on the next wave

• In a transverse wave:

  • The wavelength can be measured from one peak to the next peak

• In a longitudinal wave:

  • The wavelength can be measured from the centre of one compression to the centre of the next

• The wavelength is given the symbol $\lambda$ (lambda) and is measured in metres (m)

Graphical Representation of Transverse Waves

• The amplitude and wavelength of a transverse wave can be represented graphically

• The distance along a wave is typically put on the x-axis of a wave diagram

A Diagram of a Transverse Wave

Diagram showing the amplitude and wavelength of a transverse wave

Frequency

• Frequency is defined as:

  The number of waves passing a point in a second

• Frequency is given the symbol $f$ and is measured in hertz (Hz)

Wave Speed

• Wave speed is the speed at which energy is transferred through a medium

• Wave speed is defined as:

  The distance travelled by a wave each second

• Wave speed is given the symbol $\nu$ and is measured in metres per second (m/s)