Light

Light and seeing We need light to see. Light comes from the sun and other light sources. Light bounces from objects and surfaces into our eyes. When light enters our eyes we see the world around us. Different surfaces reflect different amount of light. This is why some things look shiny and bright, and others look dull. At night the moon reflects some sunlight and stars give a little light, but there is usually not enough light to read or to work. Warning: you must never look directly at the sun. It is so bright it can make you blind.

Light sources Sun Light bulbs Candles Lamp Flame Stars

Properties of light Light travels in straight lines.(waves) Light travels extremely quickly (its speed300,000 km per second) Light can travels through vacuum. Light is form of energy.(particles of energy) Light can pass through transparent materials but cannot pass through opaque objects. Light bounces back when made to fall on polished surfaces such as mirrors or metal surfaces. This bouncing back of light is described as reflection.

Light and materials Opaque: Do not let the light to pass through it. Transparent: Let the light to pass through it. Translucent: Let some of the light to pass through it while the other bounced.

(light sources – reflect – straight) Activities After you learned about light you can answer those questions!!! Q: Fill in the blanks: (light sources – reflect – straight) The sun, light bulbs and candles are _______________. We see the objects around us because they ___________ the light from a light source into our eyes. Light travels in ___________ lines.

Q: Draw arrows to show how the girl uses light from the sun to see the tree.

Q: Mark each of these statements as true (T) or false (F). The sun is a light source. ( ) Light travels in circles. ( ) Alexander Graham Bell invented the electric bulb. ( ) When you read a book the book is reflecting light into our eyes. ( ) Our eyes produce light. ( ) A mirror absorbs light. ( ) Shiny metal reflects light. ( ) Sun is not a source of light. ( )

Translucent Opaque Transparent Q: Put each material in the correct column. ( window – glass – metal – milk – tissue paper – black cloth – rock – air) Transparent Translucent Opaque