Magic trick? The results of this experiment are pretty surprising. Kids (and adults) will stare in amazement and scratch their heads wondering what causes the arrow in this experiment to change direction right before their eyes!
Exploring refraction couldn’t be easier or more fun. Preview the experiment with our demonstration video below and find an easy to understand explanation of how it works below.
- Piece of Paper
Step 1 – Get a sheet of paper and draw two arrows on it. One arrow near the top and one arrow near the bottom. Make the arrows point in the same direction.
Step 2 – Fill a glass with water.
Step 3 – Slowly lower the piece of paper behind the glass of water.
Step 4 – Look through the glass of water and watch what happens. Do you know why the arrow appears to change directions? Find out the answer in the how does this experiment work section below.
The scientific concept that is at work in this experiment is called refraction. Refraction is the bending of light. Refraction occurs when light travels from one medium to another (ie. air to water, water to air).
During the experiment, the light traveled from the image through the air, then through the glass cup into the water, and finally out of the glass cup and into the air once more before it reached our eyes. Light refracts as it passes from one medium to the next because it travels at different speeds through those mediums. Light travels fastest through air, a little slower through water, and even slower through glass.
This means that the light bends once when it travels through the glass cup into the water, and then it bends again when it travels out of the glass cup and into the air. As a result, the light paths cross and the image appears to be flipped horizontally (left/right).
I hope you enjoyed the experiment. Here are some printable instructions: