Question

If the velocity and wavelength of light in air is $v_a$ and ${\lambda }_a$, and that in water is $v_w$ and ${\lambda }_w$. Then the refractive index of water is

• A. $\frac{v_w}{v_a}$
• B. $\frac{v_a}{v_w}$
• C. $\frac{{\lambda }_w}{{\lambda }_a}$
• D. $\frac{v_a{\lambda }_a}{v_w{\lambda }_w}$

Answer 1

Answer: (B)

According to Snell's law
${}_a{\mu }_w=\frac{v_a}{v_w}=\frac{{\lambda }_a}{{\lambda }_w}=\frac{{\mu }_w}{{\mu }_a}$
or ${\mu }_w=\frac{v_a}{v_w}\left(\because {\mu }_a=1\right)$