Question

The speed of light in a transparent medium is given as $2.4\times {{10}^{8}}m{{s}^{-1}}$. Calculate the absolute refractive index of the medium.
A. 1.5
B. 0.8
C. 1
D. 1.25

Answer 1

Hint: In order to solve this problem, we have to know the equation of refractive index
$n=\dfrac{c}{v}$
Here c is the velocity of light in vacuum and v is the velocity of light in a given transparent medium. Substitute the given values in the equation.

Complete step-by-step answer:
The refractive index of a material is a dimensionless quantity in which it describes the velocity of light through a medium. It is given by the equation,
 $n=\dfrac{c}{v}$
Where c is the velocity of light in vacuum and v is the velocity of light in a given transparent medium Refractive index is having a number of applications in daily life. It is mostly used for identifying a particular substance, and to confirm its purity, or to measure its concentration. Especially it helps to measure the concentration of a solute in a solution which is aqueous. So here as given,
$v=$$2.4\times {{10}^{8}}m{{s}^{-1}}$
$c=3\times {{10}^{8}}m{{s}^{-1}}$
and we know the equation of refractive index is
$n=\dfrac{c}{v}$
Substituting the values here will give,
$n=\dfrac{3\times {{10}^{8}}}{2.4\times {{10}^{8}}}$
$n=\dfrac{3}{2.4}$
Therefore the refractive index of the transparent medium is
$n=1.25$.
So the correct answer is option D.

Note: If the refractive index is higher, then the light travels will be slower, which becomes the reason to have increased change in the direction of the light within the media. It means that material having a higher refractive index can bend the light more. The concept of refractive index is used for identifying a particular substance, and to confirm its purity, or to measure its concentration. Especially it helps to measure the concentration of a solute in a solution which is aqueous.