Sound
Sound is a
phenomenon that stimulates the ear.
Waves
Sound
travels in waves through a medium such as a solid, liquid or gas.
Two basic
waves are transverse and longitudinal
Transverse Waves
An example
of a transverse wave is a rippling effect on water.
The waves
are straight up and down from the line along which the wave is travelling
Longitudinal waves
An example
of a longlitudinal wave is a slinky.
The waves
push back and forward and hit neighbour molicules to transfer the energy of the
wave.
The molicules
do not move much once the energy has passed through them
Compression and Rarefaction
Compression
is the increase in density
Rarefaction is
the decrease in density
This is what
waves are made up of.
Wavelength, Velocity and Amplitude
Wavelength
is the distance between a point in a wave that occurs more than once e.g. the
start of a wave and when it repeats itself
Wavelength is
measured on metres (m)
Velocity is
the speed of the wave.
In steel a wave
travels just under 5000 m/s
In water a wave
travels around 1500 m/s
In air it
travels around 333 m/s
Velocity is
measured in metres per second (m/s)
Amplitude is
the perceived ‘loudness’ of a wave
Amplitude is
measured in metres (m)
Frequency is
the number of vibrations per second is in a wave
Frequency is
measured in Hertz (Hz)
This leads
us on to the equation
v=fx λ
Standing Waves
Standing waves are stationary waves
They disturb a medium but do not travel through them
An example of this is a guitar string.
These waves have a node (min) and an anti-node (max)
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