Ask A Scientist Physics Archive

name         Kristina W.
status       student
age          10

Question -   How does color absorbs the light and turns it into heat?
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Kristina,

Light itself is a form of energy. Scientists have discovered that one form of energy can be 
converted into another. There are several different kinds of energy. Some examples are: chemical 
energy, electricity, light, and heat. All forms of energy are convertible into heat.
For example, the chemical compounds in food can be acted upon by your body to convert the food's 
energy into energy that enables your body to function. Some of the food's energy is converted 
into heat energy that warms your body.
The chemical reactions going on inside a car battery or flashlight battery enable those batteries 
to make electricity. When electricity is passed into a light bulb, electrical energy is 
converted into light and heat.
Now, to answer your question: When light falls on an object, some of the energy of the light 
may be absorbed (soaked up) by the object. This absorbed energy raises the energy of the 
substances in the object. In turn, the object sends out the absorbed energy as heat energy.
Dark colored objects absorb light and convert it into heat better than light colored objects. 
Light colored and very shiny surfaces tend to reflect light. As a result, less is absorbed and 
less is converted into heat. You can demonstrate this for yourself by covering a thermometer 
with different colored pieces of paper and then placing it in sunlight for about 10 minutes. 
Expose each color for the same time and see which one gets hotter.

Regards,
ProfHoff 638
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Kristina,
Things are made of atoms.  The atoms shake around, banging into each other all the time.  
High temperature atoms shake faster than low temperature atoms.  Light is a wave, like waves 
on a string.  Light waves are much smaller and much faster, but they still vibrate.  When the 
vibrating light is absorbed by the atoms, it makes the atoms shake faster.

Dr. Ken Mellendorf
Physics Instructor
Illinois Central College
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