Science Experiments - Dark & Light Surfaces

Do you know why some houses have tin roofs or some painted black? Why do outdoor athletes mainly were bright colours while performing/practising (white, cream, yellow)? The fact is that some colours tend to absorb more heat than others. Scientific experiments have proven that dark surfaces tend to absorb more light while shiny, bright surfaces reflect the heat energy. Why not try out this small experiment to see if this is true?

Materials Needed : 2 identical jars filled with equal amounts of cold water
1 sheet of black paper and 1 sheet of shiny, foil paper
2 thermometers
Light Source (Eg. Small Lamp)

 Procedure : Fill equal quantities of slightly cold water into the 2 jars and cover one of them with the black paper, and the other with the shiny paper (as shown in the diagram). Label the jars (A - black and B-foil) as well as the thermometers and record the temperatures. Place both the jars at the same distance from a light source (a lamp, tubelight etc.) and after an hour, re-check the temperatures. You will see that the water temperature in A will increase while that in B remains relatively the same.

How did this happen?
Dark surfaces absorb more heat and so the black paper absorbs heat and transmits the heat to the jar and water. Heat energy that falls on the shiny foil paper bounces back, therefore unaffecting the water temperature.

NOTE: The light source should be placed close to the jars otherwise the results will not be satisfactory. A single thermometer can be used but the readings may not be highly accurate since you will have to wait for the mercury to reach normal temperature before using it again, and this may be time-consuming.

So next time you are going out to play or going on vacation, make sure you wear the right colour clothes!