Wave Optics - Result Question 17

17. In Young’s double slit experiment the distance between the slits and the screen is doubled. The separation between the slits is reduced to half. As a result the fringe width [NEET Kar: 2013]

(a) is doubled

(b) is halved

(c) becomes four times

(d) remains unchanged

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Answer:

Correct Answer: 17. (c)

Solution:

  1. (c) Fringe width $\beta=\frac{\lambda D}{d}$;

From question $D^{\prime}=2 D$ and $d^{\prime}=\frac{d}{2}$

$\therefore \beta^{\prime}=\frac{\lambda D^{\prime}}{d^{\prime}}=4 \beta$