<P> Where, D (\ displaystyle D) is the angle of deviation at an arbitrary angle of incidence i (\ displaystyle i), and n (\ displaystyle n) is the refractive index of the prism . </P> <P> It may be noted that minimum deviation in a rectangular slab is zero as both the surfaces separating two media are parallel, whereas, in a prism they are inclined to each other . </P>

How does angle of deviation vary with angle of incidence