How Light Helps Us (1972)

[Music] is there a burglar in David's home [Music] oh it's David himself and his friend Mark a flashlights fun to play with and it's useful too without light we can't see [Music] we use different kinds of lights inside and outside many of the things we see give off [Music] light some lights tell us things [Music] to see clearly we need a certain amount of light when the TV picture's made darker it's hard to [Music] see when it's made very bright it's also hard to see very bright light is hard on the eyes when someone takes your picture with a flash you blink sunglasses help protect our eyes from Bright [Music] Light you probably learned that it's not safe to look at the sun directly even during an eclipse when the sun is partly hidden most of the things we see we see by sunlight [Music] sunlight shows us things that don't give off light themselves sunlight passing through this glass helps us see its color light passing through this slide helps us see the [Music] picture we see by light from the viewer that passes through the slide [Music] we can recognize many materials by the way light passes through [Music] them light passing through a material helps us see what the the material looks [Music] like suppose we have something that light doesn't pass through it looks dark when the light is blocked but on the other side we see the light the light reflection bounces off the shiny plastic the plastic reflects light this is another way that light helps us see things we can find many objects that are good reflectors of [Music] light these things don't give off light themselves they're simply reflecting light that hits them that's how we see them [Music] different objects reflect light in different [Music] ways this material is too rough to show the flashlight clearly but it still reflects its light what about this paper do we see it because of light it gives off Itself by light coming through or by light reflected from [Music] it how about this cloth what happens to the light hitting [Music] it we learn about materials by light that passes through and by light that's reflected seeing how light is reflected from different things helps us see what kinds of materials they are [Music] light helps us see by the way it's reflected from things [Music] light helps us see by the way it passes through things [Music] we can also see things that give off light themselves light also helps us in other ways it helps things grow for instance how does this help us [Music] la [Music]