Question

light enters from air into a glass plate having refractive index 1.50. What is the speed of light in glass????​

Answer 1

Answer:

$2 \times {10}^{8} \sf\underline{ \rm {m/s}}$

Explanation:

$\sf{ \rm {refractive \: index \: of \: glass = \frac{speed \: of \: light \: in \: air}{speed \: of \: light \: in \: glass} }}$

$\sf{ \rm {so, \: 1.50 = \frac{3 \times {10}^{8} }{speed \: of \: light \: in \: glass} }}$

$\therefore\sf{ \rm {speed \: of \: light \: in \: glass = \frac{3 \times {10}^{8} }{1.50}m/s}}$

$= \sf\underline{ \rm {2 \times {10}^{8} m/s}}$

Thus, The speed of light in glass = 2×10⁸m/s

Answer 2

→Refractive index of a medium (nm) = Speed of light in vacuum/Speed of light in the medium

→Speed of light in vacuum (c) = 3 × 108 m/s

→Refractive index of glass (ng) = 1.50

→Speed of light in the glass (v) = Speed of light in vacuum/ Refractive index of glass

=> $\large\mathcal\purple{c/ng}$

=> 3 × 108/1.50 = 2x 108 ms-1