Question

A narrow slit of width 2 mm is illuminated with monochromatic light of wavelength 500 nm. If the distance between the slit and the screen is 1 m, then first minima are separated by a distance of

• A. 5 mm
• B. 0.5 mm
• C. 1 mm
• D. 10 mm

Hint:

For diffraction problems, always ensure you're using the correct units for wavelength and slit width.

Answer 1

The Correct Option is A

The angular distance between the minima for single-slit diffraction is given by the formula: $$ \Delta y = \frac{\lambda L}{a} $$ where $\lambda$ is the wavelength, $L$ is the distance to the screen, and $a$ is the slit width. Substituting the values $\lambda = 500 \, \text{nm}$, $L = 1 \, \text{m}$, and $a = 2 \, \text{mm}$, the first minima separation is calculated as 5 mm.