How does critical angle relate to refractive index of a material?Explain.

Asked by ashwati | 10th Apr, 2009, 12:58: PM

Expert Answer:

We know that, refractive index = sin i / sin r

Now, let us consider a ray of light incident at an angle ic ( critical angle) from glass to air, for which the angle of refraction is 900.

So, the refractive index of air w.r.t. glass = sin ic  / sin 900.

but, sin 900 = 1

so, the refractive index of air w.r.t. glass = sin ic  / 1

or, the refractive index of glass w.r.t air = 1/ sin ic 

so, knowing the refractive index of the denser medium w.r.t. rarer medium ,

we can calculate the critical angle for that pair of media or vice-versa.

 

Answered by  | 12th Apr, 2009, 01:05: PM

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