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 ${\lambda }_2=\left(\frac{n_1}{n_2}\right){\lambda }_1$