A beam of light having wavelength $5400 Å$ from a distance source falls on a single slit $0.96 \mathrm{~mm}$…
A beam of light having wavelength $5400 Å$ from a distance source falls on a single slit $0.96 \mathrm{~mm}$ wide and the resultant diffraction pattern is observed on a screen $2 \mathrm{~m}$ away. What is the distance between the first dark fringe on either side of central bright fringe?
4.8 mm
1.2 mm
2.4 mm
3.6 mm
Solution
$\lambda=5.4 \times 10^{-7} \mathrm{~m}, \mathrm{D}=2 \mathrm{~m} \text { and } \mathrm{a}=0.96 \times 10^{-3} \mathrm{~m}$
Distance between the dark fringes on either side of the central bright fringe $=\frac{2 \lambda \mathrm{D}}{\mathrm{a}}=2.4 \mathrm{~mm}$