Light

By David Carlson

Light is emitted from many different sources. It comes from the

sun, the moon, flashlights, light bulbs, and other things. It is essential to our

everyday life. Without it we would stumble around and have no clue what is

going on around it.

The main source of light on Earth is the Sun. Without it their would be

no life on Earth. Light travels at 186,282 miles per SECOND. Nothing can

travel faster than this. According to Einstein this is the cosmic "Speed limit".

Lights speed is invariant. This means that light get emitted at the same speed

from a moving object that it does from a stationary object. Scientists do not

know why. This is one of the main principles of Einstein's Theory of

Relativity.

Light is emitted in to forms, particles and waves. The particles are

called photons. Light comes in both forms. This is called the dual nature of

light. Photons can be observed by atoms, while waves radiant energy. The

frequency of visible light is very small it comes in 7 main wavelengths. Red

,orange, yellow, green, blue, indigo, violet. To the extremes of these are ultra-

violet and inferred with we cannot see.

Light Has many uses. We need it to live. Plants use it to make food

and keep themselves alive. We and other animals use it to see. We use it for

energy in solar cells for electricity or to heat water. It is an inexpensive

source of energy witch we can use to to replace gasoline.

Light is a small part of the energy spectrum. It is the middle range and

beside it is ultra-violet and infa-red. The extremes of this range are gamma

radiation and microwaves. Both of these are lethal to us, even though they

have very useful for cooking and energy.

If you where to put light to pass threw a prism it would divide into 7

colors. This is called a spectrum. These seven colors make up all the colors

we can see. Color is just a particular wavelength of light. Color is just a

wavelength of light that is not reflected by an atom of a substance. For

example a red item will reflect red light and absorb all the other and a blue

object will reflect blue light and absorb all other light.

When you mix all the different light colors together you get white

light. Other stars emit white light while the sun mostly emits yellow and red

with some blue in it.

Light will boucle off an object at the opposite angle in witch it hit the

object. If it hits at 90 degrees it will bounce off at 90 degrees. Light does not

loose speed or energy when it hits an object.