A ray of light of frequency 5 × 1014 Hz is passed through a liquid. The wavelength of light measured inside the liquid is found to be 450 × 10−9 m. The refractive index of the liquid is
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 1.33
The frequency does not change when light enters a medium; the speed and wavelength change. So the speed in the liquid is \( v = \nu\lambda \), and the refractive index is \( n = c/v \).
\( \displaystyle v = 5\times10^{14}\,\mathrm{Hz} \times 450\times10^{-9}\,\mathrm{m} = 2.25\times10^{8}\,\mathrm{m\,s^{-1}} \)
\( \displaystyle n = \frac{c}{v} = \frac{3\times10^{8}}{2.25\times10^{8}} \approx 1.33 \)