# What change in nature of a wave occur when it change its medium?

When a wave of a particular wavelength and frequency change its medium which results in the change of wavelength but not frequency. Since the wavelength is characteristic of a wave then will nature of wave also change by changing wavelength? I mean if it is a ultraviolet, will it become radio wave or some other wave? Because both have difference in wavelengths

Change in wavelength, sure happens, and depends on the refractive index of the medium. But the change from ultraviolet to infrared, or microwave is so huge (of the order of ten to the power 7) and that's somewhat impossible.

The ratio of wavelengths of a wave in vacuum and in some other linear medium is equal to the refractive index of the medium. If the transition of wavelength is from $10^{-9} m$ (ultraviolet) to $10^{-2}m$ (microwave), that corresponds to a medium of having refractive index of the order of $10^{-7}$. This means the velocity of the wave have changed by the order of $10^7m/s$. The velocity of the wave then through the medium is somewhat of the order of $10^{15}m/s$. That's obviously cannot happen as it is much far greater than the speed of light in vacuum.

The smallest value of refractive index is one, for vacuum, since we compare the wavelength or velocity of a wave in vacuum with that in some medium to mention the refractive index of the medium. So, that much drastic change in wavelength is not possible.

Equations used:

$$\frac{\lambda_0}{\lambda}=n=\frac{c}{v}$$

where $n$ is refractive index of the medium; $\lambda_0$ and $\lambda$ are thewavelengths of the electromagnetic wave in vacuum and medium respectively; $v$ and $c$ are the velocities of the wave through the medium and through vacuum respectively.

• what about the other way around (from microwave to ultraviolet)? – philip_0008 Jul 30 '16 at 18:40
• that's also impossible as it need a material of refractive index of the order of $10^7$. A material of that much refractive index offers huge resistance. Such transmitting substances are not possible since the velocity of light through such a medium will be about $10^-{15}m/s$. – UKH Jul 31 '16 at 2:00