Question

A beam of light of wavelength $600$nm from a distant source falls on a single slit $1$ mm wide and the resulting diffraction pattern is observed on a screen $2$ m away. The distance between the first dark fringes on either side of the central bright fringe is?

• A. $1.2$ cm
• B. $1.2$ mm
• C. $2.4$ cm
• D. $2.4$ mm

Answer 1

The correct option is C $2.4$ cm

Linear width of central maxima

$2y=\frac{2\lambda D}{a}=\frac{2\times 600\times {10}^{-9}\times 2}{1\times {10}^{-3}}=2.4cm$