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A ray of light traveling from glass into ethyl alcohol is...

A ray of light traveling from glass into ethyl alcohol is incident at the boundary at an angle of incidence 30o. Calculate the angle of refraction.

[Refractive index of glass =1.5; refractive index of ethyl alcohol = 1.36]
 

A.

27o

B.

33.5o

C.

51.7o

D.

72.8o

Correct answer is B

The angle of incidence l = 30º
The angle of refraction , r =?
The refractive index of glass ng = 1.5
The refractive index of ethyl alcohol, ne = 1.36
from snell's law :

neng=sinisinr

\frac{1.36}{1.5} = \frac{sin30º}{sinr}

1.36sinr = 1.5 x sin30º

sinr =  \frac{1.5 \times sin30º}{1.36}

sinr = 0.5515

r = sin^{-1}(0.5515)

r = 33.5º