Huygen's wave theory of light could not explain

Options

A. Photoelectric effect
B. Polarisation
C. Diffraction
D. Interference

Answer

To solve the question regarding Huygen's wave theory of light and what it could not explain, we can follow these steps:

### Step 1: Understand Huygen's Wave Theory
Huygen's wave theory posits that light behaves as a wave. This theory explains various phenomena associated with wave behavior, such as diffraction, interference, and polarization.

### Step 2: Identify Wave Phenomena
Recognize that Huygen's theory successfully explains several wave phenomena:
- **Diffraction**: The bending of waves around obstacles.
- **Interference**: The superposition of waves leading to constructive and destructive patterns.
- **Polarization**: The orientation of oscillations in a particular direction.

### Step 3: Identify Particle Phenomena
Understand that Huygen's wave theory does not account for phenomena that require a particle nature of light. The most notable example is:
- **Photoelectric Effect**: This phenomenon demonstrates that light can eject electrons from a material, which cannot be explained by wave theory alone.

### Step 4: Conclusion
Based on the above analysis, we conclude that Huygen's wave theory of light could not explain the photoelectric effect, as it requires an understanding of light as particles (photons) rather than just waves.

### Final Answer
Huygen's wave theory of light could not explain the photoelectric effect.

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