Refraction is the change in the direction of the wave passing from one medium to another.
The change in the direction of the propagation of any wave is due to the different speed at different points.
A far away object appears closer and a small object appears larger.
Take an example. Suppose, an object lies in water.
A far away object appears closer. The angle from which the rays of light reach the observer is larger than the angle that it makes in air.
This makes the angular size larger to the observer's eye which makes the object look larger relative what it looks in air. Similar but vice versa condition occurs in the case when a small object appears larger.
I don't know what u mean by primary purpose light colors but if you just asking for primary colors these are the only ones.
A commission is a where the artist is hired and paid to create artwork, where a patronage is when the artist is given financial support through others to provide these artworks.
