The velocities of light in air and glass are 3.0 x 108ms-1 and 2.0 x 108ms-1 respectively. If the angle of refraction is 30°, the sine of the angle of incidence is
-
A.
0.33 -
B.
0.50 -
C.
0.67 -
D.
0.75
Correct Answer: Option D
Explanation
Refractive index
= (frac{Sin i}{Sin r}) = (frac{text{Vel. of light in air}}{text{vel. of light in glass}})
= (frac{Sin i}{Sin 30^o})= (frac{3.0 times 10^8}{2.0 times 10^8})
= Sin i = (frac{(3.0 times 10^8 times Sin 30^o)}{2.0 times 10^8})
= Sin i = (frac{(3.0 times 10^8 times 0.5)}{2.0 times 10^8})
= (frac{1.5}{2})
= 0.75