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From Glasses to Cameras
📖 From Glasses to Cameras
Every camera, projector, telescope, and pair of glasses uses lenses. A convex lens in a magnifying glass can focus sunlight to start a fire — concentrating parallel rays to a single point. Your eye has a convex lens that focuses images onto your retina. Understanding how lenses bend light explains everything from why you need glasses to how microscopes reveal invisible worlds!
How Lenses Work
A lens works by refracting (bending) light rays. The shape of the lens determines how much and in which direction rays bend:
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🧠 Memory Aid
Convex vs Concave: Con-VEX = VEXed, it pushes rays inward (converges). Con-CAVE = CAVEd in, it pulls rays outward (diverges).
Real vs Virtual image: REAL rays Really meet. VIRTUAL rays only Virtually (seem to) meet.
Object position → image type (convex lens):
- Object beyond 2F → real, inverted, diminished
- Object at 2F → real, inverted, same size
- Object between F and 2F → real, inverted, magnified
- Object closer than F → virtual, upright, magnified (magnifying glass!)
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Quiz · Question 1 of 13
What does a convex (converging) lens do to parallel rays of light?
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This topic in real past papers
Every real exam question we've found on lenses & images, with a full worked answer.