Answer:
the change of direction of light as it passes from one medium to another is associated with a change in velocity and wavelength. The energy of the light is unchanged as it passes from one media to another. When visible light in air enters a medium such as glass, the velocity of light decreases to 75% of its velocity in air and in other materials the decrease can be even more substantial. For example, in linseed oil, the velocity decreases to 66% of its velocity in air. Figure 2 displays in bar chart format the velocity of light in different media. The 100% value is the velocity of light in vacuum. For air, the velocity is 99.97% of the speed in vacuum. For some pigments such as titanium (Ti) white, the velocity decreases to 40%.
