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: 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
