What Do You Know About The Speed Of Red And Blue Light (i) In Vacuum, (ii) In Glass? The Refraction Index Of Glass For Blue Light Is 1.665 And For Red Light Is 1.645. (The Speed Of Light In Vacuum Is ).

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What do you know about the speed of red and blue light (i) In vacuum, (ii) In glass? The refraction index of glass for blue light is 1.665 and for red light is 1.645. (The speed of light in vacuum is ).


Correct option is


(i) In vacuum, the speed of light of all colours (or of all wavelengths) is the same. Hence in vacuum, the speed of both red and blue light is   

(ii) According to wave-theory, the speed of light in glass is given by   


Where c is the speed of light in vacuum (on air) and n is the refractive index of glass. The refractive index of glass for blue light is 1.665. hence the speed of blue light in glass is  


The refractive-index of glass for red light is 1.645. Hence the speed of red light in glass is


Clearly in glass red light travels faster than blue light. 




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