Describing Waves (WJEC GCSE Physics: Combined Science)

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

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  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) 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 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  and is measured in metres per second (m/s)