Case : Read the passage and answer the question(s).

The properties of a light such as its speed, frequency and wavelength and properties of the medium like its refractive index give us a lot of information about the interaction of light with that medium. Consider a monochromatic ray of light travelling in vacuum with speed c, wavelength λ and frequency v, enters into a medium of refractive index 1.5. 

What will be its new wavelength?

2λ/3

Since frequency is constant $\frac{c}{\lambda} = \frac{v}{\lambda'}$

$λ' = λ\frac{v}{c} = \frac{\lambda}{\mu} = \frac{2\lambda}{3}$