A ray of light traveling from glass into ethyl alcohol is incident at the boundary at an angle of incidence 30\(^o\). Calculate the angle of refraction.
[Refractive index of glass =1.5; refractive index of ethyl alcohol = 1.36]
A
27\(^o\)
B
33.5\(^o\)
C
51.7\(^o\)
D
72.8\(^o\)
Verified Correct Answer: B.
Physical Principles & Numerical Solution
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 :
\(\frac{n_e}{n_g} = \frac{sini}{sinr}\)
\(\frac{1.36}{1.5} = \frac{sin30º}{sinr}\)
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
Source: WAEC / JAMB / NECO Classroom Archive (Record #59411)