properties of waves
The wavelength of a wave is the distance from a point on one wave
to the equivalent point on the adjacent wave.
The amplitude of a wave is the maximum displacement of a point on
a wave away from its undisturbed position.
The frequency of a wave is the number of waves passing a point
The wave speed is the speed at which the energy is transferred (or
the wave moves) through the medium.
wave speed = frequency × wavelength
v = f λ
wave speed, v, in metres per second, m/s
frequency, f, in hertz, Hz
wavelength, λ, in metres, m
transverse and longitudinal waves
The ripples on a water surface are an example of a transverse wave.
Longitudinal waves show areas of compression and rarefaction.
Sound waves travelling through air are longitudinal.
Waves may be either transverse or longitudinal.
Within the ear, sound waves cause the ear drum and other parts
to vibrate which causes the sensation of sound. The conversion of
sound waves to vibrations of solids works over a limited frequency
range. This restricts the limits of human hearing.
Sound waves can travel through solids causing vibrations in the solid
The range of normal human hearing is
from 20 Hz to 20 kHz.
reflection of waves
Waves can be absorbed or transmitted at the boundary between two
be able to draw ray diagrams
Waves can be reflected at the boundary between two different materials.
Waves for detection and exploration
Echo sounding, using high frequency sound waves is used to detect
objects in deep water and measure water depth.
are produced by earthquakes. P-waves are
longitudinal, seismic waves. P-waves travel at different speeds
through solids and liquids. S-waves are transverse, seismic waves.
S-waves cannot travel through a liquid. P-waves and S-waves
provide evidence for the structure and size of the Earth’s core.
have a frequency higher than the upper limit of
hearing for humans. Ultrasound waves are partially reflected when
they meet a boundary between two different media. The time taken
for the reflections to reach a detector can be used to determine how
far away such a boundary is. This allows ultrasound waves to be
used for both medical and industrial imaging.