The color purple, or equivalently violet, is
actually on the end of the visible electromagnetic
spectrum, having the highest frequency of any
light wave. The reason we see different colors is
because of this difference in frequency, where
violet light has higher frequency of light waves
than blue light. Red is the first color in the
visible spectrum, having the lowest frequency of
light waves. Ultraviolet waves have a higher
frequency than that of violet waves, however,
produce light waves that are invisible to the
human eye, and therefore not on the color
The frequency in each light wave is directly
related to how much energy a light wave has.
If the wave has a large frequency, then the wave
is oscillating very rapidly back and forth,
meaning it has a lot of energy. This energy
is then felt in the form of temperature, or heat.
Thus the colors of light with the highest
frequency will have the hottest temperature. From
the visible spectrum, we know violet would glow
the hottest, and blue glows less hot.
As this is true for all forms of light, its
application is seen in fire, or when an object is
heated up. A fire will start to glow red at first,
which is the lowest temperature of light waves. If
the fire got hotter and hotter, the flames would
start glowing in different colors, going from
orange, to yellow, to white. This is the same for
a metal that is heated up. Known as black body
radiation, a body of metal will heat up and
give off red light at its lowest temperature, and
produce higher frequency light at higher
temperatures. Violet light can sometimes glow at
around 71,000 degrees Farenheit. For reference
our sun burns at 8,500 degrees Fahrenheit,
glowing in white and yellow!
It's not - purple light is actually more
energetic than blue light.
Are you thinking of how weather maps often
draw extremely cold temperatures as purple?
It's just convention (the answer has to do with
how colors on computer screens work). Ice reflects
blue light, so cold temperatures are associated
with blue. Fire emits red light. However, note
that the fire is emitting the light rather than
just reflecting it: a flame that is hot enough
will emit blue light, and is hotter than the
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