Question

Look at the diagram below. It shows a ray of light about to enter a glass block. As the light waves enter the glass block they __________ in speed. What is the missing word?

Answer 1

Answer:

You can say that they "change" in speed or "slow" in speed.

Note wavelength where y is the wavelength and N the index of refraction:

N1 y1 = N2 y2

If N1 is air (N1 = 1) and N2 = 1.33 then

y1 = 1.33 y2

Since y2 is less the speed will be smaller