Question

2. Define ‘refractive index of a transparent medium ‘ What is its unit ? Which has a higher refractive index , glass or water

Answer 1

Answer :

$\bigstar\:\underline{\boxed{\bf{\red{Refractive}\:\blue{Index}\green{:}}}}$

➳ Refractive index of a medium is defined as the factor by which speed of light reduces as compared to the speed of light in vacuum.

➳ In other words, Refracrive index is defined as the ratio of speed of light in vacuum to the speed of light in medium.

➳ More (less) refractive index implies less(more) speed of light in that medium, which therefore is called denser (rarer) medium.

$\dag\:\boxed{\tt{\eta=\dfrac{c}{v}=\dfrac{speed\:of\:light\:in\:vacuum}{speed\:of\:light\:in\:medium}}}$

➳ Refractive index of medium is an unitless as well as dimensionless quantity.

⇒ R.I. of water = 4/3 = 1.33

⇒ R.I. of glass = 3/2 = 1.5

$\dag\:\boxed{\bf{RI_{glass}>RI_{water}}}$

Answer 2

$\large\bf\underline{\green{Refractive \: \: \: Index:}}$

The ratio of the speed of light in in air air to the speed of light in given medium .

Refractive index of medium 2 with respect to medium 1.

$\implies \bf \: \mu \: = \frac{speed \: of \: light \: in \: medium \: 1}{speed \: of \: light \: in \: medium \: 1} = \frac{v1}{v2}$

Note :- Refractive index has no units.

▪︎Refractive index of glass = ≅ 1.5

▪︎Refractive index of water = ≅ 1.33

Hence Refractive index of glass is more.

ADDITIONAL INFORMATION :-

➵ Diamond has higher optical density.

➵ Vacuum Has lowest optical density.

➵ Diamond has higher refractive index

➵ Vacuum has lowest refractive index