Huygen's theory of secondary waves can be used to find-

Options

A. velocity of light
B. the wavelength of light
C. wave from geometrically
D. magnifying power of microscope

Answer

To solve the question regarding Huygen's theory of secondary waves, we can break it down into the following steps:

### Step-by-Step Solution:

1. **Understanding Huygen's Principle**:
- Huygen's principle states that every point on a wavefront can be considered as a source of secondary wavelets. These wavelets spread out in the forward direction at the same speed as the original wave.

2. **Identifying Wavefronts**:
- A wavefront is defined as the surface over which an oscillation has a constant phase. According to Huygen's principle, the new wavefront can be constructed from these secondary wavelets.

3. **Constructing the New Wavefront**:
- To find the new wavefront, we consider all the secondary wavelets emitted from each point on the original wavefront. The new wavefront is formed by drawing a tangent to all these wavelets.

4. **Geometric Interpretation**:
- The geometric interpretation of Huygen's principle involves using the tangents to the wavelets to visualize the new wavefront. This can be done by connecting the points where the wavelets would meet at a later time, thus forming a new wavefront.

5. **Conclusion**:
- Huygen's theory can be used to find the new wavefront geometrically by constructing it from the secondary wavelets.

### Final Answer:
Huygen's theory of secondary waves can be used to find the wavefront geometrically.

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