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. $\frac{2 n }{\mu}, \frac{\lambda}{\mu} \text { and } v$

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, $\mu=\frac{\text { velocity of light in vacuum }}{\text { velocity of light in medium }}$
$\lambda_m=\frac{v}{\mu}$