Bending Light – Potty Science Club

19/05/202110:0018/05/2021 13:31Leave a Comment

Hello and welcome to Potty Science session number 3! Be sure to check out our previous experiments if you missed them.

In this session we will be experimenting with water again using equipment and items you can find in your own home. All our experiments are conducted in a home environment and not in a laboratory and will be safe and simple, reflecting an item or exhibit held in the Museum’s collection.

Some birds and animals on display in the museum gallery hunt and catch fish. Looking for your prey through water could be difficult but the Heron and Kingfisher are experts at this. For you and I looking for your dinner from a river bank or pond side would not be so simple. In this experiment we will be looking how water distorts what we see because of refraction of light through the water.

What you will need for this experiment:
1. A plastic bottle full of water. Make sure the top is tight on your bottle of water so you don’t spill any water during the experiment.
2. A piece paper.
3. A colouring pen or pencil.

First, take the piece of paper and draw two arrows pointing opposite ways as shown in the picture below:

Next, stand or stick the paper with arrows on or against a support, with the paper orientated so that the arrows are on the lower half of the paper.

Place the bottle of water in front of the arrowed paper; you may need to move it either back of forward to get the best result.

Move the bottle of water slowly across the front of the arrows and back again.

Have a look at the video below to see how I did it.

Not only are the arrows larger, they have reversed the way they are pointing.

So what’s happening?

It’s all down to light refraction and the bottle of water. Light bends when it passes through substances such as water or plastic, also when a light ray moves from air to water (which is denser) its speed changes.

The direction and speed of the light ray have changed making the arrows appear to have reversed direction.

Another example of this is when you look at the bottom of a fish pool. Light travels from the bottom of the pool, through the water then through the air to your eye. The way the light travels make the fish in the pool appear to be nearer the surface than they really are.

Sometimes you can’t really believe your eyes.

Have fun experimenting!

By Rob Gagliano, Casual Learning Development Leader and Natural Science Collections Volunteer

Written by museumvolunteers - Modified by Glenn Roadley (Curator, Natural Sciences)

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