An experiment on the refraction of light

With this experiment that looks more like magic, you’ll change the direction of an arrow without touching it! Surprise your family and friends as you learn about a phenomenon known as the refraction of light.

For this fun experiment you need:

✔ a glass cup
✔ Water
✔ A paper with the drawing of an arrow


Draw a horizontal arrow on the paper and fill your glass with water.

Keeping an eye on the glass of water, hold the paper behind it and slowly move it backwards. Observe what happens to the arrow as you move the paper. You’ll notice that after reaching a certain distance, the arrow seems to point in the opposite direction, as if by magic!

Repeat the same steps, but without water. You will notice that there is no change in the direction the arrow is pointing.


Although the result of this experiment seems magical, its foundation is in science and not in magic. It turns out that when light passes from one material to another it can bend or refract. In this experiment, light traveled from the air, through the glass, then through the water and through the back of the glass. Finally, the light returned through the air, before reaching the arrow.

Did you know that eyeglass lenses work thanks to refraction? Eyeglass lenses are pieces of glass that bend light rays enough to focus images and allow people who need it to see properly.