Why does red light travel faster than violet light in medium? Though red light has a longer wavelength than violet light, still, its frequency is lower than violet light. So, doesn't that makes them equal?
It probably does depend on which medium you're talking about, but usually higher-frequency, smaller wavelength lights feel the electromagnetic permittivity (is.gd/pTW0dJ) and permeability (is.gd/t1plmo) of the medium more than the lower frequency, larger wavelength lights.
Light always travels at only one speed. 299,792,458 meters per second. The overall progress of light can slow down through various media, but this is only because despite the common misconception light is not reflected by anything. When photons hit something, even something like a mirror, the light energy is absorbed by the molecules in the mirror, which changes their energy state, and they emit new photons. The photons that hit the mirror do not simply bounce off of it. When light is going through something the overall progress can be slowed due to all that absorption and re-emission going on. However, the individual photons are all still always traveling at the standard speed of light. Red light has a longer wavelength than violet. So the photons can travel farther through something without actually hitting any of the molecules in it. The same reason why radio waves can penetrate through walls to your radio but visible light gets blocked.
