Question

Monochromatic light of wavelength, $\lambda_{1}$ travelling in medium of refractive index, $n_{1}$ enters a denser medium of refractive index, $n_{2}$. The wavelength in the second medium is

• A. $\lambda_{1}\left(\frac{n_{1}}{n_{2}}\right)$
• B. $\lambda_{1}\left(\frac{n_{2}}{n_{1}}\right)$
• C. $\lambda_{1}$
• D. $\lambda_{1}\left(\frac{n_{2}-n_{1}}{n_{1}}\right)$

Answer 1

Answer: (A)

As, $n_{1}=\frac{C}{v_{1}}=\frac{v \lambda}{v \lambda_{1}}=\frac{\lambda}{\lambda_{1}}$
and $n_{2}=\frac{C}{v_{2}}=\frac{v \lambda}{v \lambda_{2}}=\frac{\lambda}{\lambda_{2}}$
Now, $\frac{n_{1}}{n_{2}}=\frac{\lambda_{2}}{\lambda_{1}}$ or $\lambda_{2}=\left(\frac{n_{1}}{n_{2}}\right) \lambda_{1}$