No one completely understands the nature of light. However, two theories of
light are used to explain light characteristics. The two theories of light are
referred to as the quantum theory and the wave motion theory.
QUANTUM THEORY: The quantum theory of light applies to X-ray,
radiation, and photoelectricity. This theory states that light is a steady stream
of high-speed particles and that all light sources send out a stream of these
particles. Each particle of light (quantum) is referred to as a photon.
WAVE MOTION THEORY: The wave motion theory of light involves
reflection, absorption, transmission, and polarization of light.
In the wave motion theory of light, light, wavelength, speed, and frequency
are important but interrelated characteristics.
The wave motion theory is the
theory that affects Illustrator Draftsman the most.
LIGHT: Light stimulates the perception of sight. White light is made of
equal intensities of all wavelengths within the visible spectrum. What we see
as color is light of a particular wavelength.
WAVELENGTH: Wavelength is the chief determinant of perceived color.
A wavelength is defined as the distance from the crest of one wave to the
crest of the next wave. Wavelengths are measured in nanometers (nm) which
are equal to one millionth of a millimeter. Light travels in a straight line,
and when it encounters an object or enters a new medium, say water, it may
be reflected, absorbed, or transmitted.
SPEED: The speed of light is constant until it passes through a new
medium, such as water, air, or glass. The speed of light is the product of
wavelength multiplied by the frequency.
Dividing the frequency by
the (constant) speed of light results in approximate wavelength.
FREQUENCY: Frequency is the number of wavelengths passing a given
point in 1 second.
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