For a thin prism, the angle of minimum deviation is given by δm=(μ−1)A.
At the position of minimum deviation, the angle of incidence i and angle of emergence e are equal, and the angle of refraction is r=2A.
Using Snell's law for small angles, i=μr=μ(2A).
The ratio of the incident angle to the minimum deviation is:
δmi=(μ−1)A2μA=2(μ−1)μ
Given μ=1.5, substituting the value:
δmi=2(1.5−1)1.5=2(0.5)1.5=11.5=23
Answer: 3:2