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The Tyndall Effect

The Tyndall Effect

The Tyndall Effect occurs when light passes through a transparent medium that has a lot of small particles in it, an example of this would be a flashlights beam passing through water in a jar. If we take two examples we will be able to understand it better –

  • One jar with just water
  • a second jar with water & a small bit of milk

When the beam is passed through the first jar it simply passes straight through and emerges at the other side exactly the same as when it went in. However, when we pass the same beam through the second jar something strange happens – the Tyndall effect.

As you can see from the image below, the jar on the right is plain tap water. The jar on the left is tap water plus a couple of teaspoons of milk. Even this small amount is enough to make the Tyndall effect occur.

the tyndall effect

the tyndall effect

Explanation of The Tyndall Effect

What is happening in the second jar is that the light is entering the jar and being bounced off the individual milk molecules. As we all know light is made of  spectrum of many colors, comprising all the colors of a rainbow. The portion of light that is being scattered around the inside of the jar is the blue section of the spectrum, as a result the beam has taken on a blueish tinge while it is inside the jar. This also means that the light exiting the jar is missing its blue portion, it will therefore have a more reddish color.

Everyday examples of the Tyndall Effect

This effect can be seen when the sun sets as the sky changes color depending on how low the sun is and as a result how much atmosphere the suns light must pass through.

The Tyndall Effect can also be see occurring in everyday life if you have ever noticed the blueish color of smoke coming from a 2 stroke engine, or even a four stroke engine (a our stroke showing blue smoke usually mean the piston rings are damaged or completely gone. The Tyndall Effect is also the reason why the sky blue.