Question

Light of wavelength $\lambda$ is incident on a slit of width $d$. The resulting diffraction pattern is observed on a screen at a distance $D$. The linear width of the principal maxima is then equal to the width of the slit if $D$ equals

• A. $\frac{d}{2\lambda }$
• B. $\frac{3\lambda }{d}$
• C. $\frac{d^2}{2\lambda }$
• D. $\frac{2{\lambda }^2}{7d}$

Answer 1

The correct option is C $\frac{d^2}{2\lambda }$

For the single slit diffraction,
Linear width of central maxima is
$\frac{2D\lambda }{d}=d$
$D=\frac{d^2}{2\lambda }$