Question

Light enters from air to glass having refractive index 1.50. What is the speed of light in the glass? The speed of light in vacuum is 3×10^8ms-1​

Answer 1

$\\ \underline{\underline{ \large \bold{Given \: Parameters : - }}}$

• Speed of the light in vacuum (c) = 3×10⁸ms-¹

• Refractive index of glass = $\sf n_g = 1.50$

$\\ \underline{ \underline{ \large \bold{To \: find : - }}}$

• The speed of light in the glass

$\\ \underline{ \underline{ \large \bold{Formula : - }}}$

$\\ \sf \: \: \: \: \ Refractive \: index \: of \: a \: medium \: = \dfrac{\: speed \: of \: light \: in \: vacuum}{ speed \: of \: light \: in \: the \: medium}$

$\\ \sf \: \: \: \: \ Refractive \: index \: of \: a \: glass \: = \dfrac{\: speed \: of \: light \: in \: vacuum}{ speed \: of \: light \: in \: the \: glass}$

$\\ \sf \: \: \: \: \ Speed \: of \: light \: in \: the \: glass = \dfrac{\: speed \: of \: light \: in \: vacuum}{ Refractive \: index \: of \: glass}$

$\\ \sf \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: v = \frac{c}{n _g }$

$\\ \sf \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: v = \frac{3 \times {10}^{8} }{1.50}$

$\\ \sf \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \boxed{ \pink{ \frak{\: \: v = 2 \times {10}^{8} m {s}^{ - 1} }}}$

$\\ \underline{ \underline{ \large \bold{Answer : - }}}$

$\\ \sf \: \underline { \: The \: speed \: of \: light \: in \: glass = v = 2 × 10^8 ms^{-1}}$