Select the phenomena which are explained by wave theory of light

Options

A. Speed of light in glass is less than that in vaccum
B. Light shows interference
C. Light shows diffractin
D. Photoelectric effect

Explanation

To solve the question "Select the phenomena which are explained by wave theory of light," we need to analyze each option provided and determine whether it can be explained by the wave theory of light.

### Step-by-Step Solution:

1. **Understanding Wave Theory of Light**:
- The wave theory of light, proposed by Huygens, explains light as a wave phenomenon. It accounts for various optical phenomena such as interference, diffraction, and the speed of light in different media.

2. **Analyzing the Options**:
- **Option 1: Speed of light in glass is less than in vacuum**:
- According to wave theory, light travels slower in denser media (like glass) compared to a vacuum. This phenomenon can be explained by the wave nature of light, as waves interact with the medium, causing a reduction in speed.
- **Conclusion**: This option is explained by wave theory.

- **Option 2: Interference pattern**:
- Interference is a phenomenon that occurs when two or more waves overlap and combine to form a new wave pattern. This is a direct consequence of the wave nature of light and can be observed in experiments like the double-slit experiment.
- **Conclusion**: This option is explained by wave theory.

- **Option 3: Diffraction pattern**:
- Diffraction refers to the bending of waves around obstacles and the spreading of waves when they pass through small openings. This phenomenon is also a characteristic of wave behavior and can be observed with light waves.
- **Conclusion**: This option is explained by wave theory.

- **Option 4: Photoelectric effect**:
- The photoelectric effect describes the emission of electrons from a material when it is exposed to light. This phenomenon cannot be explained by wave theory alone, as it requires the particle nature of light (photons) to account for the instantaneous emission of electrons.
- **Conclusion**: This option is not explained by wave theory.

3. **Final Selection**:
- Based on the analysis, the phenomena that can be explained by wave theory of light are:
- Speed of light in glass is less than in vacuum
- Interference pattern
- Diffraction pattern

### Final Answer:
The phenomena explained by wave theory of light are:
- Speed of light in glass is less than in vacuum
- Interference pattern
- Diffraction pattern