Mon Prof Augmenté
Light Bending Into Water
A narrow beam of light travelling through air hits the surface of water at a slant and changes direction as it enters. Below the surface it keeps going in a straight line again, but along a new path.
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Age 15: open this week
Browse Age 15
In the picture
- The green beam travelling through the air toward the tank.
- The bright point where the beam meets the water surface.
- The upright dashed line standing at right angles to the surface.
- The faint dashed line showing the path the beam would have taken without changing direction.
- The green beam inside the water, on its new steeper path to the tank floor.
Examples
- A straw in a glass of water looks broken or shifted at the surface.
- The bottom of a swimming pool looks closer to the surface than it really is.
Key takeaways
- Light travels slower in water than in air, and that is why it bends.
- The bending happens at the surface; inside the water the beam is straight again.
Carry on in the app
Three questions on this lesson. It has left the free week, so its quiz is for subscribers.
At least one new illustrated lesson every weekday for your child’s year, with its quiz and a reminder at 6:15 pm.
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