Q. A light ray of $5895Å$ wavelength travelling in vacuum enters a medium of refractive index 1.5. The speed of light in the medium is
A) $3\ \times 10^{8}{ms}^{- 1}$
B) $2\ \times 10⁸\ {ms}^{- 1}$
C) $1.5\ \times 10⁸\ {ms}^{- 1}$
D) $6 \times 10⁸\ {ms}^{- 1}$
Explanation
(b) Speed of light is given by
$v = \frac{c}{n} = \frac{3 \times \ 10^{8}}{1.5} = 2\ \times \ 10^{8}\ {ms}^{- 1}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.