Optics Question 167
Question: In a single slit diffraction of light of wavelength l by a slit of width e, the size of the central maximum on a screen at a distance b is
Options:
A) $ 2b\lambda +e $
B) $ \frac{2b\lambda }{e} $
C) $ \frac{2b\lambda }{e}+e $
D) $ \frac{2b\lambda }{e}-e $
Show Answer
Answer:
Correct Answer: C
Solution:
The direction in which the first minima occurs is $ \theta $ (say). Then $ e\sin \theta =\lambda $ or $ e\theta =\lambda $ or, $ \theta =\frac{\lambda }{e} $
$ (\because \theta =\sin \theta $ when $ \theta $ small) Width of the central maximum $ =2b\theta +e=2b.\frac{\lambda }{e}+e $
