"Light travels towards us" Return to list of pracs

Aim: This activity is used to demonstrate that light must travel towards our eyes for us to see.

Equipment: The equipment includes...  

Method: Construct the following shapes on shiny cardboard:

The cardboard is constructed with two squares of red and blue on bottom half of card. The reflection of these squares can be seen in the blank top part of the card.

Background knowledge: Light must be travelling from the coloured squares to your eye after reflecting off the top of the card. Some other facts about light include... Light always travel in straight lines. You can see light rays if you use a torch and hit a chalk board duster in front of it. It might be an idea to close the blinds. Objects that we see around us can only be seen if light from the sun or lights around us bounce off the object and go to our eye (this is why we can see the chalk dust particles and therefore the beam of light). The light then enters our eyes and focusses on the back of the eye (the retina). The messages are then delivered via the optic nerve to the brain to be interpreted. Our brain actually receives an upside down image of what we see and the brain flips it over!

So, what is light? It has been studied for centuries. Maxwell, late last century discovered that light is actually a fluctuation of electricity and magnetism in space.

What are the different colours of light? These exist because the light waves are of difference frequencies (ie. the electrical fields and magnetic fields change at a faster or slower rate).