Deviation due to Refraction

Angle of
Incidence
Angle of
Refraction
Angle of
Deviation

Graphs of angles of incidence, refraction and deviation of a ray of light passing from air in to some medium are shown here.
Blue curve shows variation of angle of refraction with angle of incidence.
Yellow curve shows variation of angle of deviation with angle of incidence.
As the angle of incidence increases the angle of refraction also increases but for a given change in angle of incidence, the change in angle of refraction is smaller for higher angles of incidence. This results in angle of deviation increasing more rapidly for larger angles of incidence
click/tap in the left/right portions of graph area to decrease/increase the refractive Index