An electro magnetic wave having frequency 1.5 x 1014 Hz is propagating in vacuum. It passes into a transparent dielectric medium having relative permitivity 2.25. Then wavelength of the wave in the medium is

For dielectric medium  μr = Relative permeability = 1Refractive index of the medium μ =εr μr= 2.25 x 1 = 1.5∴Speed of wave in the medium, v=cμ=3 x 1081.5 m/s=2 x 108 m/s∴Wavelength in the medium, λ=vf=2 x 1081.5 x 1014m=1330 nm