Before we can learn about the laser we need to know a little bit about light (since that is what a laser is made of). Light from our sun, or from an
electric bulb, is called white light. It is really a mixture of all the different colours of light. The colours range from violet, indigo, and blue, to green,
yellow, orange, and red. These make up the visible part of the electromagnetic spectrum. Light is made up of particles, called PHOTONS, which travel in waves. The difference in the colour depends on the
wavelength of the light. Violet light has the shortest wavelength while red has the longest. There are other parts of the electromagnetic spectrum which
includes infra-red, radar, television radio and micro- waves (past red on the spectrum), and on the other end of the spectrum are the other invisible
radiations, ultra- violet, X rays, micro waves and gamma rays.
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