A parallel beam of monochromatic light falls normally on a single narrow slit. How does the angular width of the principal maximum in the resulting diffraction pattern depend on width of the slit?

For diffraction at a single-slit the angular width of the principal maximum is inversely proportion to the width of the slit i.e.,
angular width θα 1/a .
Class 12 Physics Chapter 10 Wave Optics Session 2024-2025.