Question

A ray of light of wavelength $720nm$ is refracted into a medium of refractive index $\mathrm{1.5.}$ What is the wavelength for light in the medium?

• A. $720nm$
• B. $1080nm$
• C. $3600nm$
• D. $480nm$

Answer 1

The correct option is D $480nm$

Wavelength $\propto \frac{1}{\text{Refractive index}}$
$\lambda \propto \frac{1}{n}$
$\frac{{\lambda }_1}{{\lambda }_2}=\frac{n_2}{n_1}$
$\frac{720nm}{{\lambda }_2}=\frac{1.5}{1}$
${\lambda }_2=480nm$