Most people associate Ben Franklin with electricity, but his first recorded experiment was on something totally different – color and heat. You’ve probably noticed that you heat up faster in the sunlight if you’re wearing a dark shirt. Try this activity to find out why.
This was Franklin 's first experiment – to observe the effect of color on an object's heating rate. Franklin found (as you should have) that dark-colored objects sink faster and farther in the snow than light-colored objects. This means that the snow under the darkest colors of felt melts the fastest. This led Franklin to the conclusion that dark-colored objects heat faster than light-colored objects.
An illustration of Franklin 's results.
Sunlight looks white or yellow, but it is actually made up of all of the colors of the rainbow. Raindrops and prisms can split sunlight into these colors.
The colors of most objects are determined by the colors of visible light* the objects absorb and reflect. For example, an apple looks red because red light bounces off of the apple, but the apple absorbs every other color.
A prism can be used to split white light into its component colors. Image licensed under Creative Commons ShareAlike 1.0
Black objects don't reflect any light. They absorb all of the light that falls on them. By contrast, white objects reflect all colors of light and don't absorb any. Green objects fall somewhere in the middle. Dark red objects absorb more light than light red objects. In general the darker the color, the more light is absorbed and the less is reflected.
What does this have to do with heat? Heat and light are both forms of energy. Most of the light that objects absorb turns into heat. Since black objects absorb the most light, they also give off the most heat.
*From now on the term “light” refers to visible light.