Question

In a single slit diffraction experiment, a slit of width is illuminated by the Red light of wavelength $650nm$ . For what value of $a$ will the first minimum fall at an angle of diffraction of ${30}^o$?

Answer 1

The first minimum fall is given as,

$n\lambda =a\sin \theta$

$1\times 650=a\sin {30}^{\circ }$

$a=1300nm$

$=1.3\mu m$

Thus, the first minimum fall is $1.3\mu m$.