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The critical angle (in degree)of a medium for a specific wavelength, if the medium has relative permitivity 3 and relative permeability \frac{4}{3} for this wavelength, will be : 
Option: 1 15
Option: 2 30
Option: 3 45
Option: 4 60
 

Answers (1)

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C_{vacuum}=\frac{1}{\sqrt{\mu _0\epsilon _0}} \ and \ C_{medium}=\frac{1}{\sqrt{\mu _0\mu _r\epsilon _0\epsilon _r}}

and  n=\frac{C_{vacuum}}{C_{medium}}=\sqrt{\mu _r\epsilon _r} =\sqrt{\frac{4}{3}*3}=2

By using snells law 

n*sinC=1*sin(90^0)\\ \Rightarrow n*sinC=1\\ \Rightarrow sinC=\frac{1}{2}\Rightarrow critical \ angle =C=30^0

So the correct option is 2.

 

Posted by

vishal kumar

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