Reversing Arrow Illusion Experiment

• 1 clear bottle

• Water in a jug

• 1 piece of paper

• 1 marker/ pen

1. Draw two arrows, one directly on top of another, facing opposite directions on a piece of paper.

2. Place the piece of paper vertically. You may secure it against a wall.

3. Place the clear bottle about 10 cm in front of the paper.

4. Pour water from a jug until it completely covers the bottom-most arrow only. You’ll notice that the direction of the arrow changes!

When light passes through from one material to another, it can bend or refract.

In this case, the glass of water acts like a magnifying glass. When light passes through a magnifying glass, light bends towards the centre (focal point). Beyond the focal point, the image appears to reverse because the light rays that were bent pass each other.

This image helps to explain the phenomenon.

For more fun, try moving the bottle of water nearer and away from the paper and observe what happens.