Page 47 - Curriculum Visions Dynamic Book. To close the book, close the tab.

Woofer
One wavelength
and therefore would not produce an accurate sound.
Wavelength
The distance between two crests
(or other corresponding points) of a wave (see: Light waves and Sound waves). Wavelength and frequency are related. Wavelength is speed divided by frequency. The longer the wavelength, the slower the wave crests pass, and the lower the frequency.
Sound waves move at about 331m/sec. If the sound source vibrates 440 times a second (the note A), the distance between crests on a wave will be 331 (speed) divided by 440 (frequency) = 0.7
m (three-quarters of a metre). Using this method, it is possible to figure out that the wavelength of sound varies from 17m for a 20Hz tone to 1.8cm for a 20kHz tone (the normal range of hearing).
The wavelength of visible light is far shorter than sound waves.
It is 7 hundred thousandths of
a centimetre for red light, and
just 4 hundred thousandths of a centimetre for violet light. All other colours fall within this narrow band. (See also: Doppler effect of light.)
White light
Light that contains all the colours of the light spectrum. It is a
 Wavelength – The distance between two adjacent crests (or other similar points) on a wave.
mixture of all of the ‘colours of the rainbow’.
(See also: Complementary colours and Dispersion of light.)
White noise
Random noise over the whole range we can hear. The result is
a hissing sound that drowns out all other kinds of sound. (See also: Pink noise.)
Wind instrument
Any musical instrument that produces a sound as a result of setting up resonance in a column of air. (See also: Bass.)
Woodwind
Any musical instrument, including flutes and reed pipes such as clarinets. The name comes from the fact that they all used
to be made of wood. Modern woodwind instruments are often made of metal.
Flutes are made to play by blowing a narrow stream of air against the edge of the mouth hole in the flute. In the case of reed instruments the air is blown over a thin strip of flexible material until it vibrates.
 Wind instrument
– Blowing over the top
of a bottle (right) will set up vibrations in the air within the bottle. When the degree of blowing
is correct, the air in
the bottle will resonate, producing a loud sound. The same principle works, for example, for a flute and pan pipes (above).
Woofer
A loudspeaker driver 3 to 5cm in diameter. It is used for reproducing low sound frequencies.
47