Question

If the width of the slit in single slit diffraction experiment is doubled, then the central maximum of diffraction pattern becomes :

• A. Broader and brighter
• B. Sharper and brighter
• C. Sharper and fainter
• D. Broader and fainter

Answer 1

Answer: (B)

Sharper and brighter

Answer 2

Width of central maximum in diffraction patern due to single slit $= \frac{2\lambda D}{a}$ where $\lambda$is the wavelength D is the distance between screen and slit and a is the slit width.

As the slit width a increases width of central maximum decrease i.e. central maximum becomes sharper or narrower. As same energy is distributed over a smaller area therefore central maximum becomes brighter.