Question

An electromagnetic radiation of frequency $n$, wavelength $\lambda$, travelling with velocity $v$ in air, enters a glass slab of refractive index $\mu$. The frequency, wavelength and velocity of light in the glass slab will be respectively

• A. $\frac{n}{\mu },\frac{\lambda }{\mu }\text{ and }\frac{v}{\mu }$
• B. $n,\frac{\lambda }{\mu }\text{ and }\frac{v}{\mu }$
• C. $n,2\lambda \text{ and }\frac{v}{\mu }$
• D. $\frac{2n}{\mu },\frac{\lambda }{\mu }\text{ and }v$

Answer 1

Answer: (B)

We know that frequency of electromagnetic radiation remains the same when it changes the medium.
Further $\mu =\frac{\text{ wavelength of light in vacuum }}{\text{ wavelength of light in medium }}=\frac{{\lambda }_v}{{\lambda }_m}$
${\lambda }_m=\frac{{\lambda }_y}{\mu }=\frac{\lambda }{\mu }$
Similarly, $\mu =\frac{\text{ velocity of light in vacuum }}{\text{ velocity of light in medium }}$
${\lambda }_m=\frac{v}{\mu }$