At a finite distance from the source, a point source of light produces

Options

A. spherical wave front
B. plane wavefront
C. cylindrical wavefront
D. both sperical and plane wavefronts

Answer

To solve the question regarding the wavefront produced by a point source of light at a finite distance, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Wavefront**:
- A wavefront is defined as the surface over which an oscillation has a constant phase. In simpler terms, it is a collection of all points that are in the same phase of the wave.

2. **Identifying the Source**:
- We are dealing with a point source of light. A point source emits light uniformly in all directions.

3. **Considering Finite Distance**:
- The question specifies that we are observing the wavefront at a finite distance from the point source. This means we are not infinitely far away, but at a measurable distance.

4. **Analyzing Path Difference**:
- For points that are equidistant from the source, the path difference is zero. This means that all points on the wavefront will have the same phase.

5. **Shape of the Wavefront**:
- Since the light spreads out uniformly from a point source, the wavefront will take the shape of a sphere. At a distance \( R \) from the source, the wavefront will be a sphere of radius \( R \).

6. **Conclusion**:
- Therefore, the wavefront produced by a point source of light at a finite distance will be spherical in shape.

### Final Answer:
The wavefront produced by a point source of light at a finite distance is **spherical**.

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