Light in the Modern World Since the beginning of time, mankind has made use of light, from simple things such as planting crops in areas of abundant light to things as well thought out as Stonehenge on the Salisbury plains. Not being content with having to rely on natural light from the sun and stars alone, we have created our own light. Our first method was fire, in such things as candles and oil lamps. More recently, however, we have relied mainly on electricity to provide us with artificial light. The research and technology that has been invested in the making of light has discovered several things that are used everyday by people, and yet remain shrouded in mystery, not least of these, is the laser.
The laser (Light Amplification by Stimulated Emission of Radiation) is made possible by the fact that if an electron absorbed energy for any reason, it can only release it again at a specific frequency. In its simplest form, a laser consists of a rod of transparent crystal or a tube filled with gas or a liquid. A mirror is placed at one end and a half-silvered mirror at the other. The laser is “pumped” by adding energy – for example, by adding electrical energy, shining another light source into it, or by stimulating a chemical reaction. These all give the electrons enough extra energy for them to release it (when appropriate) in the form of photons. Some of the electrons spontaneously release their excess energy, emitting photons.
The photons that travel toward the sides of the laser are quickly lost, but those travelling along the length of the rod or tube are reflected back by the mirrors. When they strike other excited atoms, they stimulate these atoms to release photons of the exact same energy level (or wavelength), which travel in the same direction as the stimulating photons. The result is an intense, highly focused beam of light escaping through the half-silvered end of the laser. Because the photo wavelength is determined by the characteristics of the atoms in the “lasing” material, laser light is of a single wavelength.
The Essay on Photoelectric Effect Light Metal Energy
Photoelectric Effect Photoelectric Effect is the formation and liberation of electrically charged particles in matter, usually metals, when it is irradiated by light or other electromagnetic radiation. The term photoelectric effect designates several types of interactions. In the external photoelectric effect, electrons are liberated from the surface of a metallic conductor by absorbing energy ...
In addition, because it travels in a tight beam, it can carry a great deal of energy over a great distance without loss. Newer variations include electron lasers, in which photons are emitted when electrons are wiggled back and forth by magnetic fields, and solid-state lasers can be built into microchips. In addition, to visible light, lasers can be made that produce infrared, ultraviolet and even x-rays. Today, lasers are being used in many technologies: . A laser forms an integral part of a C. D player…
Car bodies are now welded together using ultra powerful lasers… Astronomers can now use lasers to determine the exact position of other stars, planets and even galaxies… The “Star-Wars” project (a joint USA and UK venture) uses a laser to destroy nuclear and thermo-nuclear weapons once they are airborne… Lasers are becoming a tool of surgery (eye surgery, brain surgery, etc)…
Weaker lasers are even being used as pointing devices in lessons and lectures across the globe. What lays ahead, in the future, nobody knows; but light will always be made use of and will always have a purpose.
