Question

Refractive Index of water is:
A) $1.33$
B) $1.06$
C) $1.67$
D) $1.89$

Answer 1

In the descriptive text and mathematical equations the refractive index variable is most commonly symbolised by letters $n$ or $n'$. A refractive index is the ratio between the speed of light in a vacuum and medium. If light is displayed in a medium other than vacuum, atoms of that medium constantly absorb and re-emit light particles, slowing down light speed.

Complete step by step answer:
The refractive index of the material is in optics a dimensionless number, which describes the fast light passage through a material (also known as the index of refraction or refraction index).
The water refractive index is $1.33$, which means that light passes $1.33$ times more rapidly in vacuum than in water. Increased refractive index is equal to decreased material light speed.
The formula for refractive index is
$n = \dfrac{c}{v}$
Where, $c$ is the speed of light and $v$ is the velocity of light in a specific medium.
The speed of light is faster in water. The Refractive index of water is $1.33$ and the refractive index of glass is $1.5$. From the equation $n = \dfrac{c}{v}$, we know that the refractive index of a medium is inversely proportional to the velocity of light in that medium. Hence, light travels faster in water.
Therefore the correct option is A

Note: The refractive index is an important element in the measurement of the numerical aperture in optical microscopy, and is an indicator of the objective’s light-gathering and resolving power. In most cases, air is the imaging medium for microscopy, but high-magnification targets often use oil or a related solvent between the front lens and the sample to increase resolution.