What is the Difference Between Diffraction and Interference?

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Diffraction and interference are two distinct phenomena related to wave behavior. The main differences between them are:

  1. Occurrence: Diffraction takes place when a wave encounters an obstacle or a slit, while interference occurs when waves from two different coherent sources meet each other.
  2. Source: Interference is a property originated by waves from two different sources, whereas diffraction involves secondary wavelets that originate from the same wave but occur from different parts of it.
  3. Contrast: The contrast between maxima and minima is very good in interference, while it is poor in diffraction.
  4. Fringe Width: The width of the fringes in interference is equal, while it is not equal in diffraction.
  5. Mechanism: Diffraction involves a wave and some obstacle or object which deflects the wave or bends it, while interference is the superposition of waves.

In summary, diffraction is a wave characteristic that occurs for all types of waves when they encounter obstacles or slits, and it can be observed in various wave phenomena such as light, sound, and water waves. On the other hand, interference is a phenomena that occurs when two or more coherent wave sources meet, resulting in the combination of their wavefronts and the formation of constructive or destructive interference patterns.

Comparative Table: Diffraction vs Interference

Here is a table comparing the differences between diffraction and interference:

Phenomenon Definition Origin Conditions Fringe Intensity Fringe Width
Interference The superposition of two or more coherent waves traveling in the same direction in the same medium, resulting in the formation of interference fringes. Waves from two different coherent sources. Waves meet each other and combine additively or subtractively. Variable fringe intensity, contrast between maxima and minima is good. Equal fringe width.
Diffraction The bending of light around the aperture or obstacle of size. Secondary waves from different parts of the same wave. Light passes through the edges of opaque bodies or through narrow openings. Poor contrast between maxima and minima. Unequal fringe width.

Interference occurs when two or more coherent waves traveling in the same direction in the same medium superpose, resulting in the formation of interference fringes. In contrast, diffraction happens when light bends around the aperture or obstacle of size. The main difference between the two phenomena is their origins: interference is caused by the superposition of waves from different sources, while diffraction is caused by the bending of waves around obstacles or through narrow openings.