A student studies that the speed of light in air is 300000 kms/ sec where that of speed in a glass slab is about 197000 kms/ sec. What causes the difference in speed of light in these two media?

Q. A student studies that the speed of light in air is 300000 kms/ sec where that of speed in a glass slab is about 197000 kms/ sec. What causes the difference in speed of light in these two media?

A.            difference in density

B.            difference in temperature

C.            difference in amount of light

D.            difference in direction of wind flow

Answer: difference in density