Optics Question 655
Question: We combined a convex lens of focal length f1 and concave lens of focal lengths f2 and their combined focal length was F. The combination of these lenses will behave like a concave lens, if
[KCET 2000]
Options:
A) f1 > f2
B) f1 < f2
C) f1 = f2
D) f1 $ \le $ f2
Show Answer
Answer:
Correct Answer: A
Solution:
$ F=\frac{f _{1}f _{2}}{f _{2}-f _{1}}, $ F will be negative if $ f _{1}>f _{2} $
