Question

For a colour of light, the wavelength in air is $6000\stackrel{\circ }{A}$ and water is $4500\stackrel{\circ }{A}$. What will be the speed of light in water?

• A. $2.25\times {10}^{8}m/s$
• B. $5\times {10}^{14}m/s$
• C. $4\times {10}^{8}m/s$
• D. None of the above

Answer 1

The correct option is A $2.25\times {10}^{8}m/s$

We know that, $\nu \propto \lambda$
$\Rightarrow \frac{{\nu }_1}{{\nu }_2}=\frac{{\lambda }_1}{{\lambda }_2}$
or ${\nu }_2=\frac{{\nu }_1\times {\lambda }_2}{{\lambda }_1}=\frac{3\times {10}^8\times 4500}{6000}$
$=2.25\times {10}^{8}m{s}^{-1}$.