Question

After a beam of UV light with the wavelength of 300 nm in the vacuum travels from vacuum into a glass, its wavelength changes to 250 nm. What is the refractive index of this glass for this light beam? Please keep 2 significant figures.

Answer 1

Answer:

1.2    

Explanation:

First find the frequency of UV light as follows:

$f=\frac{c}{\lambda}\\f=\frac{3\times10^8}{300\times10^{-9}}=10^{15}Hz$

The frequency does not change when light enters from vacuum into glass.

$v=f\lambda\\v=10^{15}\times 250\times10^{-9}=2.50\times10^8m/s$

Refractive index of glass can be calculated as follows:

$\mu=\frac{c}{v}$

where, v is the velocity of UV light in glass.

$\mu=\frac{3\times10^8}{2.5\times10^8}=1.2$