Question

Absolute refractive index of ruby is 1.71. What can you say about the speed of light in ruby?
a) It is slower by a factor of 1.71 relative to that in air.
b) It is higher by a factor of 1.71 relative to that in air
c) It is same as its speed in air
d) It is slower by a factor of 5.5 relative to that in air.

Answer 1

Answer:

Given,

Refractive Index (R.I)of Ruby = 1.7

Speed of light in Vaccum (C) = 3 \times 10^{8} m/s.

Speed of light in Ruby (V_{R}) = ?

R.I = \frac{(Speed of light)_{vaccum}}{(Speed of light)_{medium}}=\frac{C}{V_{R}}

R.I = \frac{C}{V_{R}}

1.7= \frac{3\times 10^{8}}{V_{R}}

V_{R}=\frac{3\times 10^{8}}{1.7}

V_{R}=1.764 \times 10^{8}m/s