A plane electromagnetic wave has a wavelength of (600,\text{nm}) in vacuum. It propagates in water whose refractive index is (n=1.33). Find (i) its wavelength in water and (ii) its frequency.

Step-by-step solution

1. Step 1: Convert the vacuum wavelength to metres: (600,\text{nm}=6.00 $imes10^{-7}$,\text{m}).
2. Step 2: Use (${\lambda }_{\text{medium}}={\lambda }_0$/n). Compute (${\lambda }_{\text{water}}$=(6.00 $imes10^{-7}$)/1.33=4.511 $imes10^{-7}$,\text{m}).
3. Step 3: The frequency is unchanged by the medium, so (f=c/$lambd{a}_0$).
4. Step 4: Calculate (f=(3.00 $imes10^8$)/(6.00 $imes10^{-7}$)=5.00 $imes10^{14}$,\text{Hz}).

Concept tested: Wavelength and frequency in different media

Published 14 September 2026 · Last updated 16 September 2026 · How this solution was prepared and checked