Wave Optics Ques 27
27. A beam of light of $\lambda=600 $ $nm$ from a distant source falls on a single slit $1$ $ mm$ wide and the resulting diffraction pattern is observed on a screen $2 $ $m$ away. The distance between first dark fringes on either side of the central bright fringe is:
[2014]
(a) $1.2$ $ cm$
(b) $1.2$ $ mm$
(c) $2.4 $ $cm$
(d) $2.4$ $ mm$
Show Answer
Answer:
Correct Answer: 27.(d)
Solution:
- (d) Given: $D=2$ $ m ; d=1 $ $mm=1 \times 10^{-3} $ $m$
$\lambda=600$ $ nm=600 \times 10^{-6} $ $m$
Width of central bright fringe =$(2 \beta)$
$=\frac{2 \lambda D}{d}=\frac{2 \times 600 \times 10^{-6} \times 2}{1 \times 10^{-3}} $ $m$
$=2.4 \times 10^{-3}$ $ m=2.4 $ $mm$
BETA
