Question

In a double slit experiment, the two slits are 1 mm apart and the screen is place 1 m away. A monochromatic light of wavelength 500 nm is used. What will be the width of each slit for obtaining ten maxima of double slit within the central maxima of single slit pattern?

• A. $0.5mm$
• B. $0.2mm$
• C. $0.02mm$
• D. $0.1mm$

Answer 1

Answer: (B)

$d={10}^{-3}m$

$D=1m$

$\lambda =500\times {10}^{-9}m$

The width of central maxima in a single slit diffraction: $\frac{2\lambda D}{a}$

Fringe width in double slit pattern: $\beta =\frac{\lambda D}{d}$

Given,

$10\beta =\frac{2\lambda D}{a}$

$\Rightarrow 10\frac{\lambda D}{d}=\frac{2\lambda D}{a}$

$\Rightarrow a=\frac{d}{5}mm=0.2mm$