Optics Question 208
Question: Radius of central zone of circular zone plate is $ 2.3mm. $ Wavelength of incident light is $ 5893{AA}. $ Source is at a distance of $ 6m. $ Then the distance of first image will be
[RPMT 2001]
Options:
A) $ 9m $
B) $ 12m $
C) $ 24m $
D) $ 36m $
Show Answer
Answer:
Correct Answer: A
Solution:
$ f _{1}=\frac{r^{2}}{\lambda }=\frac{{{(2.3\times {{10}^{-3}})}^{2}}}{5893\times {{10}^{-10}}}=9m. $
