Optics Question 204
Question: Which statement is correct for a zone plate and a lens
[RPMT 2002]
Options:
A) Zone plate has multi focii whereas lens has one
B) Zone plate has one focus whereas lens has multiple focii
C) Both are correct
D) Zone plate has one focus whereas a lens has infinite
Show Answer
Answer:
Correct Answer: A
Solution:
Multiple focii of zone plate given by $ f _{p}=\frac{r _{n}^{2}}{(2p-1)\lambda } $ , where $ p=1,2,3…… $
