Properties of Light and Medium

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                          When rays of light fall upon "Object", it follows parallel path until it find change in medium. In fact, this deviation of light from one medium to another is caused by numerous factors.
                         Some of these factors mentioned are as below :



  • Focus 
  • Focal Length
  • Refraction
  • Refractive Index



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Focus

                     
                      The term "Focus" can be defined as "Aggregation" of rays of light when they travel from one medium to another depending upon value of "Refractive Index".

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Focal Length 

                   
                      The term "Focal Length" can be referred to as distance between "Center of Lens" and "Focus".


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Refraction 

                   
                      It is the property of light rays to deviate itself towards the "Principle Axis" when they travel from one medium to another.


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Refractive Index

                   
                      The term "Refractive Index" can be defined as ratio of Velocity of light in "Medium" to the Velocity of Light in "Air".Mathematically it can be represented as, 
                      

                                                                   u = Vm / Va 

                                                                                      Where,
                                                                   Vm = Velocity of light in medium.
                                                                    Va  = Velocity of light in air.