Q. In an experiment to demonstrate interference of flight using Young's slits, separation of two slits is doubled. In order to maintain same spacing of fringes, distance $D$ of screen from slits must be changed to :

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A

$D$

B

$\frac{D}{2}$

C

$2 D$

D

$\frac{3 D}{4}$

Solution:

In YDSE, we know fringe width is given as
$\beta=\frac{\lambda D}{d}=\frac{\lambda(2 D)}{2 d}=\beta $
$\Rightarrow D^{\prime} =2 \,D$

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(b) interference
(c) diffraction
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2. In Young's double slit experiment, how many maxima can be obtained on a screen (including central maxima), if $\text{d} = \frac{5 \lambda }{2}$ (where $\lambda $ is the wavelength of light)?

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If she observes that y = $\beta'$ the wavelength of light used is :

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