Mon Prof Augmenté
Three Red Beams Crossing After a Lens
Three parallel beams of red light travel toward a thick glass lens and pass through it. The curved glass bends each beam so that all three meet at one bright point on the other side, then spread out again.
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Age 15: open this week
Browse Age 15
In the picture
- The lamp housing that sends out the three beams
- One of the parallel beams before it reaches the glass
- The thick glass lens that bulges on both sides
- The single point where the three beams cross
- The white card catching the spread-out beams
Examples
- A magnifying glass focusing sunlight into a tiny hot spot on paper
- The lens in a camera or phone bringing distant light to a sharp point on the sensor
Key takeaways
- A converging lens bends parallel rays so they meet at one point, called the focal point
- The distance from the lens to that point is the focal length, and a fatter lens has a shorter one
Carry on in the app
Three questions on this lesson. It has left the free week, so its quiz is for subscribers.
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