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How does interference demonstrate the wave properties of light?

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A horizontal gradient bar displays the visible light spectrum from violet to red, labeled with corresponding frequency in terahertz, wavelength in nanometers, and photon energy in electron volts. — light When white light is spread apart by a prism or a diffraction grating, the colours of the visible spectrum appear. The colours vary according to their wavelengths. Violet has the highest frequencies and shortest wavelengths, and red has the lowest frequencies and the longest wavelengths.

Interference demonstrates the wave nature of light through the superposition principle, which describes how overlapping waves combine in space. When light waves meet, they produce interference patterns that are characteristic of wave behavior rather than classical particles.123

There are two primary forms of this interaction:
* Constructive interference: Occurs when wave crests coincide, resulting in a combined wave with an amplitude equal to the sum of the individual waves.12
* Destructive interference: Occurs when a crest coincides with a trough, causing the waves to annul each other.12

These effects are fundamental to physical optics and are observed in phenomena such as diffraction, where light waves spread and interfere after encountering an obstacle or aperture. While classical wave models explain these patterns through superposition, quantum mechanics reveals that even individual photons contribute to these patterns, representing the probability of their arrival at a specific point. This behavior confirms that light exhibits wave-like properties, even as it defies simple classical categorization.423