Lenses and eyes Lesson 22 of the physics course of Mova's primary school: 17 sentences, each with its syntax tree and pragmatics. The lessons are written for Mova, and their agreed trees are part of Mova corpus 0.4 (CC BY-SA 4.0). How Mova does on its tests: the lesson at school .
0 A lens is a piece of clear glass or plastic with curved sides that bends light on its way through; a lens thick in the middle gathers the light inwards. 1 Hold a magnifying glass over an ant and the bent light makes the ant look huge, but the same lens can gather sunlight into a tiny burning spot, so it is never pointed at the Sun or anything alive. 2 Your eye has its own lens that makes a sharp, upside-down picture on the back of the eye, and your brain turns it the right way up. 3 If an eye is a little too long or too short the picture lands in the wrong place, and glasses bend the light just enough to put it right. 4 Telescopes and microscopes put lenses or mirrors together to show what our eyes alone cannot: craters on the Moon, or tiny creatures swimming in a drop of pond water. 5 A magnifying glass is thicker in the middle and bends light inwards, making small things look bigger. 6 A magnifying glass can focus sunlight into a hot spot that starts fires, so it is never pointed at the Sun or at anything living. 7 The lens in your eye makes an upside-down picture on the back of the eye, and the brain turns it the right way up. 8 The pupil, the dark hole in the middle of your eye, grows bigger in the dark and smaller in bright light. 9 Glasses bend light a little so that it focuses properly in eyes that are slightly too long or too short; short-sighted people see near things well, long-sighted people see far things well. 10 Looking straight at the Sun, even with sunglasses, can burn the back of the eye without any pain, and the damage can be permanent. 11 An eclipse of the Sun is watched only with special eclipse glasses or a pinhole projector. 13 A telescope gathers much more light than your eye and makes the picture bigger, and Galileo saw the moons of Jupiter with a small one in 1610. 14 A microscope uses two lenses, each making the picture bigger again, and shows that a drop of pond water is full of tiny living things. 15 A laser makes a narrow beam of light of one colour that hardly spreads, and it must never be shone into anyone's eyes or at planes. 16 Light can travel along thin glass threads, called optical fibres, bouncing inside them, and the internet uses such fibres under the sea. 17 A mirage of water on a hot road is light from the sky bent by hot air near the road, which is why the puddle vanishes as you get closer. ← previous Mirrors, rainbows and the blue skynext → Heat moves: hot to cold↑ back to Physics This page in Markdown → https://md.mova.elamur.ai/free/en/corpora/school/physics/22-lenses-and-eyes/