Is this true? all electromagnetic waves travel at same speed in glass? why?

Question

Is this true? all electromagnetic waves travel at same speed in glass? why?

Answer 1

All electromagnetic radiation have same speed in an homogeneous medium. That speed is c (speed in vacuum) / refractive index

Answer 2

Not true, EM waves are light.  Light travels at different speeds in glass based on wavelength.  Because of this you can see the different colours of light when light is shined on a prism.

Answer 3

Em waves travel in vacuum at (approximately) c=3*10^8 m/s .

But in a homogeneus glass the speed is decreased to v=c/n , where n is the indice of the material (some materials have different indices for different wavelengths).

But this is the answer to How? , the answer to why is:  only Allah knows

Answer 4

Yes.God made it this way.