Wave Optics - Result Question 30
32. 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:
(a) $1.2 cm$
(b) $1.2 mm$
(c) $2.4 cm$
(d) $2.4 mm$
[2014]
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Answer:
Correct Answer: 32. (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 $(=2 \beta)$ $=\frac{2 \lambda D}{d}=\frac{2 \times 600 \times 10^{-6} \times 2}{1 \times 10^{-3}} m$
$=2.4 \times 10^{-3} m=2.4 mm$
