A ray of light is incident normally on a face of an equilateral prism. The ray gets totally reflected at the second refracting surface. The total deviation…

60°

Reason — As, the ray is normally incident on face AB so it passes undeviated. Angle of incidence on face AC is 60˚. The reflected ray is incident normally on face BC and passes undeviated.

Now, from the above diagram,

∠NRS = 60˚

∴ ∠SRC = 30˚

∠ARQ = 30˚

∴ ∠CRT = 30˚

RT is the original path of the incident ray.

So, total deviation = ∠SRT = 30˚ + 30˚ = 60˚