Laser ,Types and Use

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  LASER :-                    LASER is an acronym of  Light Amplification by stimulated emission of Radiation. It is an optical device which produces an intensive beam of highly coherent, Monochromatic light[ Electromagnetic radiation, especially visible radiation, of only one frequency or wavelength]. It can travel over great distance without spread.   LASER LIGHT :-                                   1. It is very different than normal light and contains only one specific wavelength of light.                                 2. A laser light has very tight beam and is very strong and concentrated.                                 3. A laser light can go to the moon and th...
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Solar Cell and Solar Panel, Construction and Applications

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What is a Solar Cell?   
                                                        - It is a device to convert solar energy into electrical energy. These cells are made from semiconductor like silicon, gallium, germanium. Solar cells are also known as photovoltaic cells. The efficiency of solar cells made from these materials is about 10-15%. The modern solar cells are made of selenium and have an efficiency of about 25%.
The principal advantage of solar cells are that they have no moving parts, require little maintenance and work without the use of the focusing device. Another advantage is that they can be set up in remote and inaccessible places easily where power transmission is expensive. 

 Construction
- To make a solar cell, thin layers (also called wafers) of a semiconductor having impurities are arranged in such a manner that a potential difference develops between the two regions of the semiconductor when light falls on it.
A typical solar cell consists of a 2cm square piece of pure and can develop 0.7W of electricity and potential of 0.5-1 V when light falls on it. 
Silicon is the most commonly used material to manufacture solar cells. It has the advantage that it is environmental-friendly and is also available in abundance, but the availability of special grade silicon for making solar cells is limited.
Uses of solar cells are
1. They provide electricity in artificial satellites and space probes.
2. These are used for street lighting, for traffic signals, for operating water pumps, etc.
3. They provide electricity to lighthouses situated in the sea.
4. They provide radio and TV transmission to remote areas. 
5. These are used to operate electronic watches and calculators.

 Solar Panel
When solar cells are arranged cell side by side, connecting each other in such a way that total potential difference and the total capacity to provide electric current is much increased, then this arrangement is called solar panel. It provides much higher power for many practical uses.
- The largest solar furnace in the world is located in France.
The entire process of manufacturing solar panel is very expensive because silver is used for interconnection of the cells in the panel.

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