
A Rolling Car Model of Light Bending
Easy
How does a magnifying glass make things look bigger? Light changes speed when it passes through a lens. That speed change bends the light path. Your eye follows the bent rays outward to where a larger object would be.
You can model this with a toy car and a cardboard ramp. Spread glue on one half of the cardboard and cover it with salt or sugar. Tilt the ramp and roll the car at an angle across the boundary.
On the gritty side the car slows down and its path curves. On clean cardboard the car rolls straight. This shows how a change in speed causes a change in direction, the same principle that makes lenses work.
Hypothesis
The hypothesis is that when light passes through a lens, its speed changes and it bends.
Science Concepts Learned
Refraction
Light changes speed when it passes from one material into another, and that speed change bends its path. A toy car on a cardboard ramp makes this visible. Spread glue on one half of the cardboard and cover it with salt or sugar, then roll the car at an angle across the boundary. On clean cardboard, the car rolls straight. On the gritty side it slows down and its path curves. That change in speed causing a change in direction is the same principle that makes lenses work.
Method & Materials
You will build a model of bending light by creating a ramp with salt or sugar and rolling a toy car or truck down it.
You will need a toy car or truck, a flat piece of cardboard, glue, and salt or sugar.
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See what’s includedResults
The experiment showed that when the car went down the salt/sugar ramp, its path bent. On the clean cardboard, the car just went in a straight line down the ramp, without changing direction. This shows that when the speed of light is changed by the lens, it changes its direction slightly.
Why do this project?
This science project is interesting and unique because it uses a simple model to demonstrate a complex scientific concept.
Also Consider
Experiment variations to consider include using different materials for the ramp, such as sand or rice, and using different objects to roll down the ramp, such as marbles or balls.
Full project details
Additional information and source material for this project are available below.Related videos
These videos explain the science behind this project and demonstrate key concepts used in the experiment.
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