Question

In a single-slit diffraction experiment, the width of the slit is reduced by half. Which of the following needs to be done if the width of the central maxima has to remain the same?

• A. Reduce the distance between the slit and screen by half
• B. Reduce the distance between the slit and the screen to $\left(\frac{1}{4}\right)^{\text {th }}$ the original separation
• C. Double the distance between the slit and the screen
• D. No need to do anything, as the width of the central maxima does not depend on the slit width

Answer 1

Answer: (A)

Reduce the distance between the slit and screen by half

Answer 2

Width of central maxima
$\beta=\frac{2 \lambda D}{a}$
Width of central maxima
$=\frac{2 \lambda(D / 2)}{(a / 2)}$
$=\frac{2 \lambda D}{a}$