SCIENCE: LIGHT & SOUND.
CEIP Santa Ana Madridejos
LIGHT & SOUND. 1.- LIGHT.
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Light is a type of energy (radiation) that some bodies can emit and is visible to the human eye. Thanks to light, we can see shape, colour and size of every object. . This kind of energy can produce changes into living beings . (photosynthesis in plants, changes in the color of our skin) . and can be transformed into other kinds of energies like thermal or electric energy. Natural light source 1.1.- WHERE LIGHT IS PRODUCED. Every body that can produce light is called light source. There are natural sources like the Sun, stars, a lightnight… or artificial sources like bulbs, candles… . The rest of bodies reflect light. In a dark room we can’t see anything because objects don’t reflect light, but we can see them under a light… In the same way, we can see the moon because it reflects sunlight Artificial light source
1.2.- PROPAGATION OF LIGHT. Light propagates from one place to another. Light moves in this way: a .- Light moves straight: we can see straight rays of light in a foggy day, or from the headlights of a car. b.- Light moves in all directions: the light from a candle in a dark room moves in all directions to everywhere. c.- Light moves very fast ( 300.000 km per second, through vacuum). Light doesn’t need any support to move (air, water, solids…). Light from a lighthouse propagates straight and in all directions. 1.3.- MATERIALS AND LIGHT. When light gets to an object, this object responds depending on the material. We classify materials in three groups: A.- Transparent materials: they allow light to pass through the material, and we can see clear images through them (water, glass…). B.- Translucent materials: they allow light to pass through the material, but you can’t see clear through them (some kinds of plastic or glass). C.- Opaque materials: they don’t let the light to pass through the material, and you can’t see anything through them. They produce a shadow (a dark space behind an opaque object with light in front of it (wood, metals…) Transparent Translucent Opaque