Energy and Change Light Electricity Energy
Introduction
Questions to
think about
How we see
Reflection
Refraction
Colour
Rainbows
Changing colour
Seeing in colour
Making rainbows
Colour & energy
Scattering light
What is light?
Summary
Conclusion
Light > Colour > Scattering light PD  |  Assessment  |  Home

Activity 5: Scattering of light***

Why is the sky blue? Why are sunsets red?
What to use Hints
Beaker of water (500 mL), light box with the end wide open, milk or soluble milk powder, white cardboard screen.
What to do
Investigate what happens if the light from the open end of the light box is shone through a beaker of water.

  1. Let the light through the beaker fall on a white cardboard screen and observe the colour of the light.
  2. What happens if small amounts of milk are added to the beaker of water and stirred gently.
    Light passing through a beaker of water when milk is added
  3. Are there any changes in the colour of the light passing through the milk onto the screen as more milk is added to the water? At the same time, what do you notice about the colour of the light as seen from the sides of the beaker of milk?

  1. What colour light is most likely to be scattered to the side as the light from the Sun passes through the atmosphere? Suggest how this makes the sky appear blue.
  2. You tend to look towards the Sun to see a beautiful sunset. How does the milky water demonstration explain why sunsets are mostly reds?

Scattering of light
The milk solution is full of microscopic particles (which makes it look milky). These particles scatter the light from the blue end of the spectrum to the side, whereas the light from the red end of the spectrum passes through the milk solution.

The atmosphere is also full of particles, air molecules and dust particles.

Challenge
What happens to the colour of the Sun when there is a bushfire nearby? Suggest a reason for this.


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