Refraction
Fact or fiction
Meet Mr. Light, one of the most fascinating personalities in the physics family.
Refraction, reflection and absorption
are a couple of things he can do. He behaves like a wave and particle at the same time. He can burn you until you are lobster red but is needed to make plants grow. He looks white but is actually made of multiple colors. He is full of energy, and when it comes to speed...stand back Michael Schumacher. Let's give it up for Mr. Light...
In this project you are going to look at just one concept surrounding one part of light, namely refraction of
white light
. But I hope you now have a small glimpse of how amazing light is, just to get you a little excited about science, because lets face it, one project about one concept doesn't quite cover this vast subject. To see another project to do with light check out
You light up my shirt
.
Anyway ... let's not be distracted from our purpose ...
Let's do science...
The project – step by step
The Question
What is refraction and what does it do?
The Hypothesis
Refraction is a bending of light when it enters
media
of different densities. This can be shown by various visual effects resulting from this bending of light.
The Experiments
Colors of the rainbow
(Don't be deceived that because something is simple it can't be used. I mean our favorite friend Sir Newton came up with the idea of gravity when an apple fell on his head!)
How to make a rainbow
(Again, this is aimed at grade 4 level, but definitely can be used here to show a phenomenon of refraction)
Magic coin
Broken pencil
Why these experiments?
The first two experiments have a look at rainbows, the most spectacular effect caused by refraction. The next two are easy to set up for a demonstration and with some simple diagrams (which of course I give you) can be used to explain this concept to even the not so bright people that come look at your display.
The Conclusion
All of the experiments show that when light enters a medium of different
density
, it will change direction or bend. This was shown in the first experiment when the different colors of light bent at different angles because of their varying wavelengths, resulting in them being separated into a rainbow. The bending of light was also noticed when the appearance of the two objects (coin and pencil) were affected as shown in the experiments.
“Beef up your project” facts
There are seven colors in a rainbow: violet, blue, cyan, green, yellow, orange and red.
In case you didn't get it from the conclusion: the seven colors of light all have different wavelengths and so bend at different angles as the speed they are traveling is changed, red bending the least and violet the most. (If you are not sure how this works check out the explanation in “Beef up your project” facts in the project -
Look at all the pretty colors! Refraction and rainbows.
Let me tell you about some amazing animals that have to deal with refraction on a daily basis, and if they don't, will be extremely hungry. When I say animals, I actually mean birds (oh, and a certain species of fish).
Any bird that takes its food out of the water by diving for it, needs to compensate for the fact that the fish is not going to be where it looks like it is! Kingfishers, the African Fish Eagle, Gulls etc. all have to sort this minor problem out when they want a snack.
The Archer fish is in the water and its food is usually outside the water. This is the guy that spits water at his food and shoots it down, usually some unsuspecting bug on a leaf. The light will bend when it leaves the water and hits the air. So before the hungry fish can snack, he has to do his geometry first. Is that why fish is known as brain food?
Look it up
So what is the point of knowing about all this if you can't apply it, right? You need some real life examples: check out the workings of binoculars and periscopes.
More...
To add some spice to your display, how about making your own periscope? A tube, some sticky tape and glue and a pair of scissors will do the trick. Obviously you will also need
prisms
, which would really impress the judges. You can make a periscope with mirrors but then you need to understand that it is
reflection
and not refraction that you would be using.
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