The relative refractive index of the two media is 0.80. In one of them, light has a wavelength of 6000 A' and travels at 2.4 x 10⁸ m/s. This light is refracted into the second medium. Its frequency in the second medium is 

The relative refractive index=0.80

The wavelength of light = 6000 A^I

The speed of light in the first medium = 2.4 x 10⁸ m/s

Now, as we know that the frequency does not change with a change in refractive index, we can find the frequency in the second medium by putting the respective values in

f = c/$\lambda$

f = $\frac{2.4 \times {10}^8}{6000 \times {10}^{-10}}$Hz

f = 4 x 10¹⁴Hz