Optics Question 678
Question: A beam of parallel rays is brought to a focus by a plano-convex lens. A thin concave lens of the same focal length is joined to the first lens. The effect of this is
[KCET 2004]
Options:
A) The focal point shifts away from the lens by a small distance
B) The focus remains undisturbed
C) The focus shifts to infinity
D) The focal point shifts towards the lens by a small distance
Show Answer
Answer:
Correct Answer: C
Solution:
$ \frac{1}{F}=\frac{1}{f _{1}}+\frac{1}{f _{2}} $
