light wave length and refrective index relationship in Fiber optics

hi all;
i dont know if it is a right place for this post or not but i think it is related to basic electronics.

i want to know about the relationship between light wave length and refractive index of the material. is the refractive index a changing property of the material?? if yes then why? if changing wavelength can change the frequency? i think it must be changed due to relation :

propagation velocity = frequency X wavelength

this relation shows us that frequency and wavelength are inversly proportional to each other..... so when light enters from one medium to other we can say that its frequency will be changed because of changed wavelength ?????? thus color of the light will be changed???

kindly solve my confusion.

thanking you in anticipation.

propagation velocity = frequency X wavelength

this relation shows us that frequency and wavelength are inversly proportional to each other..... so when light enters from one medium to other we can say that its frequency will be changed because of changed wavelength ?????? thus color of the light will be changed???

Click to expand...

Right formula, wrong conclusion. The frequency stays constant, wavelength changes with propagation speed.

Also refractive index is directly related to propagation speed, but inversely proportional. See https://en.wikipedia.org/wiki/Refractive_index