Step 1: Understanding the Concept:
Light exhibits a dual nature: wave-like and particle-like.
Classical wave theory (Huygens' Principle) successfully explains phenomena related to propagation, interference, and bending.
However, interactions involving the exchange of discrete energy packets (photons) with matter require the quantum (particle) theory of light.
Step 2: Detailed Explanation:
Reflection (A): Wave theory explains reflection using Huygens' principle, where every point on an incoming wavefront acts as a source of secondary wavelets. The envelope of these wavelets forms the reflected wavefront. The law of reflection (\(\angle i = \angle r\)) is easily derived.
Diffraction (B): This is the quintessential wave property where light waves bend around obstacles. It is explained by the interference of secondary wavelets from the same wavefront. Particle theory cannot explain why light would bend into a geometrical shadow.
Refraction (C): Explained by wave theory through the change in wave speed when entering a different medium. Snell's law is a direct mathematical consequence of wave propagation.
Compton effect (D): This involves the scattering of high-energy X-ray photons by electrons. It was observed that the scattered radiation has a longer wavelength than the incident radiation.
Classical wave theory predicts that the frequency of light should not change upon scattering.
Arthur Compton explained this by treating the X-ray as a particle (photon) that collides with an electron, transferring some of its energy and momentum.
The loss in energy of the photon results in a decrease in frequency and an increase in wavelength (\(E = hc/\lambda\)).
Because this phenomenon relies on discrete momentum transfer between individual particles, it cannot be explained by continuous wave theory.
Step 3: Final Answer:
The Compton effect requires the particle (photon) model of light and cannot be explained by wave theory.