Single-Slit Diffraction

Definition

Single-slit diffraction is a phenomenon that occurs when a wave, such as light or sound, passes through a single narrow opening or slit. This results in the wave spreading out and interfering with itself, creating a diffraction pattern on the other side of the slit.

5 Must Know Facts For Your Next Test

1. The diffraction pattern created by single-slit diffraction consists of a central bright fringe (maximum) surrounded by alternating bright and dark fringes (minima and maxima).
2. The width of the central bright fringe and the spacing between the fringes are inversely proportional to the width of the slit.
3. The wavelength of the wave and the distance between the slit and the observation screen also affect the diffraction pattern.
4. Single-slit diffraction can be used to determine the wavelength of a wave if the slit width and the diffraction pattern are known.
5. The diffraction pattern observed in single-slit diffraction is a result of the wave's interference with itself after passing through the slit.

Review Questions

• Explain the relationship between the width of the slit and the diffraction pattern observed in single-slit diffraction.
  • In single-slit diffraction, the width of the slit is inversely proportional to the width of the central bright fringe and the spacing between the fringes in the diffraction pattern. As the slit width decreases, the central bright fringe becomes wider, and the spacing between the fringes decreases. Conversely, as the slit width increases, the central bright fringe becomes narrower, and the spacing between the fringes increases. This relationship is due to the wave's ability to spread out and interfere with itself more when passing through a narrower slit, resulting in a broader diffraction pattern.
• Describe how the wavelength of the wave affects the diffraction pattern in single-slit diffraction.
  • The wavelength of the wave plays a crucial role in the single-slit diffraction pattern. As the wavelength increases, the diffraction pattern becomes more pronounced, with the central bright fringe becoming wider and the spacing between the fringes decreasing. Conversely, as the wavelength decreases, the central bright fringe becomes narrower, and the spacing between the fringes increases. This relationship is due to the wave's ability to bend and spread out more when the wavelength is longer, leading to a more pronounced diffraction pattern. By measuring the diffraction pattern and knowing the slit width, the wavelength of the wave can be determined.
• Analyze the role of interference in the formation of the single-slit diffraction pattern and explain how it leads to the alternating bright and dark fringes.
  • The single-slit diffraction pattern is a result of the wave's interference with itself after passing through the slit. As the wave emerges from the slit, different parts of the wave travel different paths and arrive at the observation screen at different phases. This leads to constructive interference, where the waves reinforce each other, and destructive interference, where the waves cancel each other out. The central bright fringe corresponds to the region where the waves interfere constructively, while the dark fringes correspond to the regions where the waves interfere destructively. The alternating bright and dark fringes are a consequence of the continuous interference pattern created by the wave as it spreads out and interacts with itself on the other side of the slit.

Related terms

Diffraction:

The bending of waves around the edges of an obstacle or through an aperture, causing the wave to spread out and interfere with itself.

Interference:

The interaction of two or more waves, resulting in a new wave pattern that is either reinforced (constructive interference) or diminished (destructive interference).

Wavelength:

The distance between two consecutive peaks or troughs in a wave, which determines the wave's frequency and behavior when interacting with obstacles or openings.