Different Hues Of The Sky- A Science Fair Project

By Author: Jason john
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If somebody ask you what is the colour of the sky, then you will surely answer that it is blue. But actually it doesn't look blue all the time. You may have also seen the sky in different colours such as red, orange, yellow and amber beneath the white clouds. Have you ever wondered where they come from? The aim of this science fair project is to show you different hues of the sky.

Materials Required:

1. A flash light
2. A transparent container with parallel sides (a 10 litre aquarium is ideal)
3. 250 ml (1 cup) of milk

How to perform the experiment?

1. Fill the container up to ¾ with water after setting it on a table where you can see it from all sides.

2. After lighting the flash light hold it against the side of the container in such a way that its beam shines through the water. Watch the beam shining through the water. May be while watching, you can see some dust particles floating in water and they appear white. However it is little bit difficult to see exactly where the beam passes through the water.

3. Pour 60ml (1/4 cup) of milk to the water and ...
... stir it well. After that, again hold the flashlight to the side of the container as you done before. You can now notice that the beam of light is easily visible as it passes through the water. Watch at the beam from both the side and from the end, where the beam shines out of the container. The beam will appear as blue from the side and somewhat yellow from the end.

4. Now add another ¼ cup of milk to the water and stir it. Then you can see the beam of light looks even bluer from the side and more yellow, perhaps even orange from the end.

Can guess the reason for the beam of light from the flash light to look blue from the side and orange from the end? The property of light is that it usually travels in straight lines, unless it encounters the edges of some material. Just think about the case when a beam of flash light travelling through air. Since the air is uniform and the light from the flash light travels in a straight line, we cannot see the beam from the side. The same thing will happen when the beam travels through water also. The water is uniform and the beam travels in straight line. But when there is some dust in the air or water, we can catch the glimpse of the beam since the light is scattered by the edges of the dust particles.

While adding milk to the water, you are adding so many tiny particles to the water since milk contains many tiny particles such as protein and fat. These tiny particles will suspend in water. These particles will cause scattering of light and made visible from the side. The scattering different colours will be different like the scattering of blue light is much more than that of red light. Because we see the scattered light from the side of the beam, and blue light is scattered more, the beam appears blue from the side. Since the red and orange light is scattered less, more red and orange light travels in a straight line from the flash light. It looks orange or red when you look directly into the beam of the flash light.