Optics Question 807
Question: A ray of light is incident on a thick slab of glass (thickness t) as shown below. The emergent ray is parallel to the incident ray but displaced. Sideways by a distance d. If the angles are small then d is:
Options:
A) $ t( 1-i/r ) $
B) $ rt( 1-i/r ) $
C) $ rt( 1-\frac{r}{i} ) $
D) $ t( 1-\frac{r}{i} ) $
Show Answer
Answer:
Correct Answer: C
Solution:
[c] The lateral displacement is given by $ d=\frac{1}{\cos r}\sin ( i-r ) $
For small angle f, angle r is also small, and so $ d=t( i-r )=ti( 1-r/i ) $
