Question

for a prism PQR the incident and emergent rays are parallel. the minimum value of refractive index of prism for angle of prism is 45

Answer 1

u = 1 / sin c {where u is the refractive index (u2/u1) and c is critical angle}  

u2/u1 = 1 / sin c  

3/2//4/3 = 1 / sin c  

9/8 = 1 / sin c  

Sin c = 8/9  

c = approx 62.73°  

incident ray is perpendicular

Therefore it won't show any refraction or any reflection

While incident ray reaches AC

It would make a triangle with angle of prism 60° and perpendicular angle now angle of incident ray with ac is 180 - 60 + 90 = 30°

Angle of incidence = 90 - 30

= 60°

Since angle of incidence is less than critical angle, Ray will NOT suffer TIR