Question 18 [CBSE, Delhi-2016, Set-1] - MCQ from Past Year Papers - Chapter 10 Class 10 - Light - Reflection and Refraction

Study the following figure in which a student  has marked the angle of incidence (∠i), angle of  refraction (∠r), angle of emergence (∠e), angle of  prism (∠A) and the angle of deviation (∠D). The  correctly marked angles are: 

(a) ∠A and ∠i 

(b) ∠A, ∠i and ∠r  

(c) ∠A, ∠i, ∠e and ∠D 

(d) ∠A, ∠i, ∠r and ∠D  

Answer

• Angle of incidence is the angle between incident ray and normal.
  So, here angle of incidence is angle i. It is marked correct
  
  
• Angle of refraction is the angle between refracted ray and normal.
  So, here angle of incidence is angle r. It is marked incorrectly

• Angle of emergence is the angle between emergent ray and normal.
  So, here angle of emergence is angle D, not angle e. So, it is marked incorrectly

• Angle of deviation is the angle between emergent ray and incident ray (when produced backwards).
  So, here angle of emergence is angle e, not angle D. So, it is marked incorrectly

• Angle of prism is the vertex angle of the prism.
  Here, it is angle A. It is marked correct
  

So, the correct answer is (a) - ∠A and ∠i