Saddam Hossain: Tutoring for Knowledge Excellence

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Si has four electrons in the outer shell of atom, after doping(P and Al) in converts into P-N type semiconductor diode . It is widely used because of its outside shell electron number , Most abundant semiconductor material and It has a bandwidth of 1.1 ev that is very efficient to collect solar radiation .

Ga As is also a Class 3 and class 5 material from periodic table .It has band width of 1.43 ev which is also very efficient to collect solar radiation .

 Ga As is more efficient than Si because of its unique property of bouncy back .Apart from normal solar cell working principle, here ,Electrons bounce back from the sun facing bottom plane of the solar cell which add a extra current flow compared to anyother solar cell .

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Eletric field and Magnetic field are two different fields with nearly same charecterstics . The coexist in electromagnetic field and propagate in right angle with one another . They are not dependent on each other . They exist separately also . Magnetic field created by a moving electric charges Or it exist around a magnetic pole . But a electric field created around a moving or static electric charges only .

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Dry ice is a solid form of Carbon dioxide(CO2) .At atmospheric pressure and -78.5 degree celcius carbon dioxide gas sublimates to solid and dry form . Its most common use is to preserve foods .

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Homogeneous mixure is a mixure where each property at any point of the mixure will be identical .

Example -

If solid salt is added in water . It will reach at the bottom of the water container . After sometime when it will disolve totally it will form homogeneous mixure of salt and water .

If sand particle is added with water . It will reach at the bottom of the water container .It will not mix up uniformly with water . So , this is called heterogeneous mixure .  

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Electric voltage difference betwwen two body creats current flow between them .Multiplication of  current and potential difference is called work done by the electric source . Work done per Second is called power . Unit of power i watt or Joule/second.

Any electric device , for examle, a 100 watt, 220 v lamp is indicating that it will consume 100 joule energy per second if connected with 220 volt line.  

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A solinoid is a Electric coil  .When current passing through the coil it will generate two magnetic poles jut like a bar magnet . The reason behind this behaviour is that moving electrons in the wire or coil creats a magnetic field around them .  

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Bauxite ,chemical formula is Al(OH)3 .

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Any ferromagnetic metal like (Iron, Nickel , Cobalt) can be magnetised by putting them in magnetic field .

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It is minus logerithm of hydrogen ion concentraion(moles/litter) with base 10 . Its range is 0 to 14 . 0-7 defines acidic solution . 7-14 defines basic solution . 7 is nuetral solution .Less the number the acidic solution is more acidic .

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Chemical formula is a way of expressing information about the proportion of atoms constitute a chemical compound using some standard symbols