What is Light?

Light is a kind of energy called "electromagnetic (EM) radiation" (but this kind of radiation is not harmful, except for an occasional sunburn). There are other kinds of EM radiation too (radio waves, microwaves, x-rays, etc.), but light is the part WE can see, the part that makes the rainbow.

Speed of Light

Light is very fast; it travels about 186,000 miles per second [300,000 kilometres per second], so light from the sun takes about 8 minutes to go 93 million miles [149 million kilometres] to earth. To see how fast light really travels lets compare it with driving a car to the sun. At a speed of 60mp/h (100km/h) it would take 177 years to get there.

Uses of Light

We depend upon light not only to see but other every day devices use light for a variety of purposes. Here are some of those devices:

• Eyeglasses and contact lenses
• Lenses for TV, movie, and photographic cameras
• Photocopiers and fax machines
• Binoculars and telescopes
• Microscopes and magnifiers
• Projectors (overhead, movie, slide, TV)
• CD players
• Supermarket product code laser scanners
• Weather and spy satellites
• Medical systems (to look inside the body)
• Solar energy systems

Plants also need light to survive and grow and they provide us with oxygen to breathe as well in a process known as photosynthesis.

Lasers: A Kewl branch of light

Regular light from the sun or a light bulb really contains all the colours of the rainbow, but to see this u have to split it up. You can do this at home with a simple glass prism, or during the next light rain shower take a look outside at a rainbow. Raindrops act like tiny prisms and break the light up into its basic colours.

A laser on the other hand is a special source of light, which is made up of only one pure colour. Unfortunately lasers are dangerous so you will not be able to test this at home for yourself.

Here are some of the Kewl properties of lasers and its uses

ENERGY!
Lasers are very powerful and contain a lot of energy. Some are so strong they can be used to cut through thick metal for example deep sea divers can user lasers to cut into ships hulls. Smaller and less powerful lasers are used as scalpels in some forms of surgery.

INFORMATION!
Lower-power laser systems can be used to send and pick up information. For example, the product code scanner in a supermarket uses a laser, lenses, rotating mirrors, and a computer to "read" bar codes from products. And the tiny laser in a CD player reads EVEN tinier bumps and holes that record the music.

COMMUNICATION!
Lasers are used today for telecommunication. Information can be sent through long threads of glass called Optical Fibers. This has proven to be very useful as thousands of telephone conversations can be sent through the same fiber at one time. In addition the Internet also makes use of lasers and optical fibers to send information

HOLOGRAMS!
Lasers are also used to make 3-D pictures called HOLOGRAMS (some engineers are working on moving holograms, so someday we may have AMAZING 3-D TV pictures)