Physics · Ch 6 — Optics
Angle of Deviation due to Refraction
Angle of Deviation due to Refraction
The angle of deviation due to refraction is the angle between the incident ray's original direction and the refracted ray's new direction. When light travels from a rarer to a denser medium, it deviates towards the normal, and the deviation is (since here). When light instead travels from a denser to a rarer medium, it deviates away from the normal, and the deviation is (since here). In both cases the deviation is measured as a positive angle re …
What this figure shows. A ray travels from a rarer medium (n1) into a denser medium (n2, with n1 less than n2), bending towards the normal so that the refraction angle r is smaller than the incidence angle i. The deviation angle marked in the figure, d = i - r, is the angle between the original (undeviated) direction of travel and the actual refracted direction -- always a bend toward the normal when light speeds up... no, when light slows down entering the dens …
What this figure shows. The mirror-image situation to Figure 6.16: a ray travels from a denser medium (n1) into a rarer medium (n2, with n1 greater than n2), bending away from the normal so the refraction angle r is now larger than the incidence angle i. Here the deviation is marked as d = r - i, the angle by which the ray has bent away from its original direction -- the two figures together show that the deviation always points in the direction of the normal on the denser side, whichever way the light happens to be travelling t …