A Ray Of Light From A Denser Medium Strikes A Rarer Medium At An Angle Of Incidence i. If The Angle Of Reflection Is r and The Angle Of Refraction Is r’and Reflected And Refracted Rays Make An Angle Of 90o with Each Other, Then The Critical Angle Will Be: 

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A ray of light from a denser medium strikes a rarer medium at an angle of incidence i. If the angle of reflection is r and the angle of refraction is r’and reflected and refracted rays make an angle of 90o with each other, then the critical angle will be: 


Correct option is


Critical angle for a pair of rarer and denser medium is given by  


Given that reflected and refracted rays make an angle of 90o, hence

Angle of reflection + angle of refraction = 90o


According to Snell’s law.   




Hence, from eq. (1) and (2), we get




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