Question

Light of wavelength $6000A$${}^{\circ }$ from a distant source falls on a slit $0.5mm$ wide. The distance between two dark bands on each side of the central bright band of the diffraction pattern observed on a screen placed at a distance $2m$ from the slit is:

• A. $1.2nm$
• B. $2.4nm$
• C. $3.6nm$
• D. $4.8mm$

Answer 1

Answer: (D)

$4.8mm$

Distance between 2 dark bands on each side of the central bright band
$=\frac{2\times \lambda \times D}{d}$
$=\frac{2\times 6000\times {10}^{-10}\times 2}{0.5\times {10}^{-3}}$
$=4.8\times {10}^{-3}m$
$=4.8mm.$