Glossary Words 7.2 • Frequency • Wavelength • In phase • Amplitude

7.2 Representing wave features Displacement-distance graphs â€˘ Convenient way of representing waves is to draw a graph of particle displacement against distance from the source.

The speed of waves • Rather than just examining one snapshot, a sequence of graphs can be used to represent a wave that is moving across to the right. ▫ Fig7.10

• In mechanical waves the speed of the wave is largely determined by the properties of the medium and, of course, by the type of disturbance that is being carried by the medium.

The frequency and period of a wave â–Ť The FREQUENCY of a wave source, f, in hertz(Hz), is the number of vibrations or cycles that are completed per second. Or, the frequency of a wave travelling in a medium is the number of complete waves that pass a given point per second.

â€˘ The time interval for one vibration or cycle to be completed is called the period, T, which is measured in seconds (s).

Frequency ▫ Where f is the frequency of the wave in hertz(Hz) ▫ T is the period of the wave in seconds (s)

Displacement-time graphs

Wavelength and amplitude • Graphs of particle displacement versus distance from the source can be used to determine the wavelength of a continuous wave. • The wavelength λ of a continuous wave is the distance between successive points with the same displacement and moving in the same direction. • These points are said to be in phase with each other. • Amplitude A, of a wave is the value of the maximum displacement of a particle from its mean position.

Complete 7.2 Questions 1-10 pg238-239