Monochromatic light of wavelength λ \lambda\,λ passes through two identical narrow slits separated by a distance ddd, producing a pattern of several fringe maxima on a screen. One of the two slits is subsequently blocked completely.
Which of the following describes the change in the observed pattern?
The central maximum becomes narrower.
The intensity of the central maximum decreases to one-quarter of its original value.
The fringe spacing decreases.
The interference fringes disappear, and a single-slit diffraction pattern remains.
