Is the larger the change of speed of a light wave the greater is refraction?

Yes, generally, the greater the change in speed of a light wave as it passes from one medium to another, the greater the degree of refraction. Refraction occurs due to the difference in the light's speed in different materials, as described by Snell's Law. A larger difference in speed results in a more pronounced bending of the light wave at the boundary between the two media. Thus, the extent of refraction is directly related to the change in speed.