Please solve and explain why i value taken as "zero degree" instead of "90 degree" The question appeared in - Physics - Ray Optics And Optical Instruments

Question

Please solve and explain why i value taken as "zero degree"
instead of "90 degree" The question appeared in 2012 Board Foreign
paper

Trace the path of a ray of light passing through a glass prism
(ABC) as shown in the figure If the refractive index of glass is 3
, find out the value of the angle of emergence from the prism

Roop Narayan · Accepted Answer

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Dear student
i= incidence angle is the angle with respect to normal that is the perpendicular line to the surface ad not with respect to surfacethus angle of incidence is 0here, it will pass undeviated till the second surfacewhere it makes 300 with normalnow,sin esin 30=3so e = 600Regards