Question

The critical angle of the material of a prism ABC is 40°. For a ray of light incident on the face AB, to emerge from the face AC, what should be the maximum value of angle A?​

Answer 1

Answer:

Here is what i understood and could evaluate

Explanation:

Answer 2

Answer:

Answer is 80degree

Explanation:

(i) Consider two cases where angle of incidence is 0  

∘

 and 90  

∘

.Then the angle of refraction (r  

1

​  

) at first face will be 0  

∘

 and C respectively, where C is the critical angle. Find the corresponding angles of refraction (r  

2

​  

) at other face of the prism. Find the angle of the prism when angle of refraction r  

2

​  

 is less than critical angle and above critical angle. A=r  

1

​  

+r  

2

​  

Get the condition, when ∠A<C and ∠A>2C. Then find what happens when ∠A is in between C and 2C.

(ii) 80  

∘