Question

what is the refractive index of vacuum?
 $\begin{align}
  & A.1.0 \\
 & B.2.0 \\
 & C.1.5 \\
 & D.0.5 \\
\end{align}$

Answer 1

Hint: The refractive index of a material is the major factor that determines how much speed should light have when it travels in that medium. It is the ratio of velocity of light in vacuum to the velocity of light in the particular medium.

Complete step by step answer:
First of all let us take a look at what the refractive index of a material is. The refractive index of a material is the major factor that determines how much speed should light have when it travels in that medium. It is the ratio of velocity of light in vacuum to the velocity of light in the particular medium. As the refractive index is higher, the slower the light wave transverse, which becomes a reason for a correspondingly higher change in the direction of the light inside the material. Refractive index is having a huge number of applications in daily life. It is mostly useful for identifying a specific substance and to confirm its purity or to take measurement of its concentration. Most commonly it is used to know the concentration of a solute in an aqueous solution. As we all know, the refractive index of the material is given by the equation, $c=v=1$
$n=\dfrac{c}{v}$
In which c is the velocity of light in vacuum and v is the velocity of light in a media.
Here $c=v=1$
Therefore the refractive index is given as one. And also as there is no medium prevailing in the vacuum, the refractive index is unity.

So, the correct answer is “Option A”.

Note: The refractive index can be less than one also if the phase velocity is speeder than the speed of light in vacuum, and hence give a refractive index below 1. Refractive index is not having a unit as it is dimensionless.