Question

In Young's double slits experiment, the position of $5^{\text{th }}$ bright fringe from the central maximum is $5cm$. The distance between slits and screen is $1m$ and wavelength of used monochromatic light is $600mm$. The separation between the slits is:

• A. $12\mu m$
• B. $60\mu m$
• C. $36\mu m$
• D. $48\mu m$

Answer 1

Answer: (B)

Given
$D=1m$
$\lambda =600\times 10^{-9}m$
$n=5$
As $y_{nth}=\frac{n\lambda D}{d}$
$\Rightarrow \frac{5\times 600\times 10^{-9}\times 1}{d}=5\times 10^{-2}$
$\Rightarrow d=\frac{5\times 600\times 10^{-9}\times 1}{5\times 10^{-2}}=60\times 10^{-6}m$
$\Rightarrow d=60\mu m$