Question

Monochromatic green light of wavelength 5 $\times {10}^{-7}$ m illuminates a pair of slits 1 mm apart. The separation of bright lines in the interference pattern formed on a screen 2 m away is :

• A. 0.25 mm
• B. 0.1 mm
• C. 1.0 mm
• D. 0.01 mm

Answer 1

The correct option is C 1.0 mm

Given,

$\lambda =5\times {10}^{-7}m$

$d=1mm=0.001m$

$D=2m$

The separation between two bright fringe is called fringe width.

$B=\frac{D\lambda }{d}$

$B=\frac{2\times 5\times {10}^{-7}}{{10}^{-3}}$

$B=1mm$

The correct option is C.