Sound:
Sound waves are longitudinal waves, their vibrations occur in the same direction
as the direction of travel.
Sound waves travel through a solid, liquid or a gas, but it cannot travel through
vacuum, as it needs a medium.
Sound is fastest in solids, and slowest in gas.
Amplitude: is the maximum height of the wave from its resting position.
➢ The greater the amplitude, the louder the sound.
Wavelength: is the distance between the crests of two waves next to each other.
Frequency: Is the number of waves per second
➢ The higher the frequency (the closer together the waves are the higher the
pitch), the higher the pitch.
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Compression: The air molecules are close together, representing areas of high
pressure in the sound wave.
Rarefaction: The air molecules are spread out, representing areas of low pressure
in the sound wave.
Units:
Loudness = DB
Frequency =Hz
1KHz= 1000Hz
Wavelength =m
Amplitude =m
Period = s
Echoes:
Sound waves can reflect off surfaces, we hear sound reflections as echoes.
Hard and smooth surfaces are good at reflecting sound, that’s why empty rooms
produce lots of echoes.
Soft and rough surfaces are good at absorbing sound, that’s why rooms with
curtains and carpets do not usually produce lots of echoes.
Jana Hassanin
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