X-ray and visible light travel at the same speed in vacuum. Do they travel at the same speed in glass?

Which light has maximum speed in glass?

P,Q and R are three particle of a medium which lie on the x-axis. A sin wave of wavelength lamda is travelling through the medium in the x-direction. P and Q always have the same speed. Whilem P and R always have the same velocity. The minimum distance between :-

Explain how Corpuscular theory predicts the speed of light in a medium, say, water, to be greater than the speed of light in vacuum. Is the prediction confirmed by experimental determination of the speed of light in water? If not, which alternative picture of light is consistent with experiment?

Minerals absorbed by the roots travel up the xylem. How do they reach the parts where they are needed most ? Do all the parts of the plant get the same amount of the minerals ?

Answer the following, giving reason:- (a) When light travels from a denser to a rarer medium, the speed increases. Does it mean that there is an increase in the energy carried by the waves ? (b) The Sun appears reddish at sunset and sunrise.