Question

Refractive index of glass is 1.65 .what is the speed of light in glass

Answer 1

you know that refractive index is inversely proportional to velocity of light. i would take it relative to air. then, n1/n2=v2/v1 = 1.65/1=3×10^8/v1 then u would get v1.hope you understand please mark brainliest.

Answer 2

Given :

$\bf Refractive \: index \: of \: flint \: glass, \: η_{g} = 1.65$

To Find :

$\bf Speed \: of \: light \: in \: glass, v_{g}$

Solution :

$\bf We \: know \: that \: speed \: of \: light \: in \: air, c=3×10⁸m/s$

Now, by formula :

$\bf η_{g} = \dfrac{c}{v_{g}}$

$\bf \implies v_{g} = \dfrac{c}{η_{g}}$

$\bf \implies v_{g} = \dfrac{3 \times 10^{8}m/s}{1.65}$

$\bf \implies v_{g} = \dfrac{3}{1.65}\times 10^{8}m/s$

$\bf \implies v_{g} = \dfrac{3 \times 100}{165}\times 10^{8}m/s$

$\bf \implies v_{g} = \dfrac{\cancel{3} \times 100}{\times{\cancel{165}}_{55}}\times 10^{8}m/s$

$\bf \implies v_{g} = \dfrac{100}{55}\times 10^{8}m/s$

$\bf \implies v_{g} = 1.8181... \times 10^{8}m/s$

$\bf \implies v_{g} = 1.82 \times 10^{8}m/s \: (approx.)$

$\bf \therefore Speed \: of \: light \: in \: glass, v_{g} = 1.82 \times 10^{8}m/s \: (approx.)$