Question

The speed of light in a transparent medium is 2.4 $\times$ 10${}^8$ m/s. Calculate absolute refractive index of the medium.

• A. 1.5
• B. 0.8
• C. 1
• D. 1.25

Answer 1

The correct option is D 1.25

The refraction index, n, of a transparent medium is defined as the ratio of speed of light in vacuum to the speed of light in that medium. The formula is $n=\frac{c}{v}$.

where the speed of light $c=3\times {10}^{8}m/s$ and v is the speed of light in the desired medium which is given as $v=2.4\times {10}^{8}m/s$.

Therefore, $n=\frac{3\times {10}^{8}m/s}{2.4\times {10}^{8}m/s}=1.25$.

Hence, the refractive index of the transparent medium is 1.25.