The behavior of light passing through one hole versus two holes can be explained by the phenomenon of diffraction, which is the bending and spreading of light waves as they encounter an obstacle or aperture. The specific differences between the two scenarios are as follows:
Single Hole (Single-Slit Diffraction): When light passes through a single hole or slit that is narrower than the wavelength of the light, it undergoes a diffraction effect known as single-slit diffraction. The light waves spread out and interfere with each other, creating a central bright spot called the central maximum or the zeroth-order maximum. On either side of the central maximum, a series of alternating dark and bright fringes, known as interference fringes or diffraction fringes, are formed. The central maximum is wider and brighter compared to the fringes.
Two Holes (Double-Slit Interference): When light passes through two closely spaced holes or slits, a phenomenon called double-slit interference occurs. In this case, the light waves passing through the two slits overlap and interfere with each other, creating a pattern of dark and bright fringes on a screen placed behind the slits. The central region between the two slits produces a series of bright fringes, called the central bright fringe or the central maximum. On either side of the central maximum, there are alternating dark and bright fringes, similar to the single-slit diffraction pattern. However, the double-slit interference pattern has narrower and more closely spaced fringes compared to the single-slit diffraction pattern.
In summary, when light passes through a single hole, it exhibits a diffraction pattern with a central maximum and interference fringes on either side. When light passes through two holes, it creates a double-slit interference pattern with a central maximum and more closely spaced interference fringes.
These phenomena demonstrate the wave-like nature of light and are fundamental aspects of the field of optics. They have been extensively studied and have contributed to our understanding of light and its behavior.