|What effect does color have on heat?|
|Question Date: 2013-05-07|
Objects can have color two ways: they can
either reflect light or emit light. Light can be
thought of as a wave. We perceive color because
of different wavelengths of light. (Keep in mind
that we can only see a small portion of the full
electromagnetic spectrum of light. See
for an example of all the different wavelengths of
When an object absorbs and reflects light, the
energy in that light is transferred to that object
and dissipated as heat. When an object absorbs
most of the light in the visual spectrum, it looks
black. If it scatters most of the light, it looks
white. Black objects absorb more heat than white
objects. If an object is orange, that object
reflects orange light and absorbs light that is
not orange. As far the effect of specific colors
on heat, it is difficult to judge for example
whether something orange or something green would
absorb more heat. It depends on whether the two
objects are the same material, the shininess of
the objects, exactly what shade of green or orange
they are, and what kind of light source is
Conversely, temperature can also have an effect on
color. Everything emits light because of its
temperature, and as something gets hotter, the
wavelength of light it emits becomes smaller and
therefore higher in energy. Right now you are
emitting infrared light, light that is just lower
in energy than red light. They even make infrared
cameras that can "see temperature"
If a black object is heated, at around 480 °C (896
°F) it will start to glow a faint red color. As
it increases in temperature the color will change
from red to orange to yellow to white to blue.
This is the reason why coals glow red,
incandescent light bulbs glow yellowish white, and
Bunsen burners glow blue. Bunsen burner flames
are hotter than light bulb filaments, which are
hotter than coals.
This question could have multiple
interpretations. First, a darker object will
absorb more radiation than a lighter colored one,
and will thus heat up faster under bright light.
Second, a very hot object that radiates heat
often has a characteristic color via black body
radiation. The color of a flame or star, for
instance, can be used to identify how hot the
Great question! Heat and color are generally
related in that you can tell the temperature of a
heat source by its color. This is how scientists
can determine, for example, the temperatures of
stars that are way too far away to measure
directly. A metal that is heated to a high
temperature can also glow with a color. For
instance, a metal with temperature around 900
degrees Fahrenheit (500 degrees Celsius) is about
a faint red glow, while metals with temperature
above 2500 F (1400 C) glow hot white.
Depends on what you mean by color.
Color is what we see as the frequency of light.
Light is composed of waves (which have a
wavelength) or particles called photons (of which
each particle carries a certain amount of energy).
Bluer light has higher frequency, shorter
wavelength, and more energetic photons, while
redder light has lower frequency, longer
wavelength, and less energetic particles. Of
course, your red light can have the same amount of
energy as a blue light, just with a larger number
of these photons and a higher amplitude (height)
of the wave.
All objects that have temperature emit light.
The hotter the object, the brighter and bluer the
light emitted will be. Most objects that you
interact with on a daily basis (including your
body) are at the right temperature to emit mainly
infrared light, which is a color too red for us to
see. Hot coals in a fire are hot enough emit red
light, molten lava is hotter still and emits
orange to yellow light, the sun is hotter yet and
emits green light, and lightning is so hot that
most of its light is actually ultraviolet, too
blue for us to see, but most of the light that we
can see from lightning is blue or violet.
Objects also reflect light that hits them,
which determines the color of the object.
Lighter-colored objects emit more light, and
darker colored objects absorb more light. The more
light an object absorbs, the more it heats up when
it is exposed to light, which is why dark things
get hot more quickly than light things if left out
in the sun. However, all of this depends on the
fact that there is something shining light onto
them (in this case, the sun); color of objects
that are not emitting light makes no difference
Objects that are more darkly colored are dark
because they reflect less visible light. This
means they absorb more light. Energy from light
striking an object is transferred to the molecules
in the object. This extra energy excites electrons
in the object's molecules and when the electrons
"fall back down" to their "ground states" the
energy is released in the form of infrared light,
or heat. The heat is then either released or the
object retains the heat. I hope this helps!
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