Question

The wavelength of light coming from sodium source is $589\text{nm}$ in air. What will be its wavelength in water$?$
Refractive index of water is $1.33$.

• A. $223\text{nm}$
• B. $333\text{nm}$
• C. $443\text{nm}$
• D. $543\text{nm}$

Answer 1

The correct option is C $443\text{nm}$

We know that,
${\mu }_{21}=\frac{{\mu }_2}{{\mu }_1}=\frac{{\lambda }_1}{{\lambda }_2}$

$\Rightarrow {\lambda }_2=\frac{{\lambda }_1\times {\mu }_1}{{\mu }_2}$

$\Rightarrow {\lambda }_2=\frac{589\times 1}{1.33}=443\text{nm}$