Q146 / 160 · AP EAMCET 2021 (19 Aug Shift 2) · Physics

In Young's double slit experiment, the separation between the slits is halved and the distance between the screen is doubled. The fringe width is

Solution

Fringe width, $β = \frac{D λ}{d}$

$\Rightarrow \frac{β_{2}}{β_{1}} = \frac{D_{2}}{D_{1}} \times \frac{d_{1}}{d_{2}}$

$\Rightarrow \frac{β_{2}}{β_{1}} = \frac{2 D}{D} \times \frac{2 d}{d}$

$\Rightarrow \frac{β_{2}}{β_{1}} = 4$

$\Rightarrow β_{2} = 4 β_{1}$

Hence, the correct answer is option: 'D'.