Optics Question 450
Question: A convex lens of focal length 1.0 m and a concave lens of focal length 0.25 m are 0.75 m apart. A parallel beam of light is incident on the convex lens. The beam emerging after refraction from both lenses is
Options:
A) Parallel to the principal axis
B) Convergent
C) Divergent
D) None of the above
Show Answer
Answer:
Correct Answer: A
Solution:
[a] Power of system. $ \frac{1}{f _{1}}+\frac{1}{f _{2}}-\frac{d}{f _{1}f _{2}}=\frac{1}{1}+\frac{1}{-0.25}-\frac{0.75}{(1)(-0.25)} $ .
Since power of the system is zero, therefore the incident parallel beam of light will remain parallel after emerging from the system.
