Question

Monochromatic light of frequency $ 5\times 10^{14}Hz$ travelling in vacuum enters medium of refractive index $1.5$. Its wavelength in the medium is

• A. $4000\,\mathring{A}$
• B. $5000\,\mathring{A}$
• C. $6000\,\mathring{A}$
• D. $5500\,\mathring{A}$

Answer 1

Answer: (A)

Frequency $(f)=5 \times 10^{14} Hz$
$\therefore $ Wavelength of light
$(\lambda)=\frac{c}{f}=\frac{3 \times 10^{8}}{5 \times 10^{14}}$
$=6 \times 10^{-7} m = 6000\, \mathring{A}$
$\therefore $ Wavelength in medium of refractive index
$\lambda'=\frac{\lambda}{\mu}=\frac{6000}{1.5}=4000\,\mathring{A}$