Spherical wavefronts, emanating from a point source, strike a plane reflecting surface. What will happen to these wave fronts, immediately after reflection?

Options

A. They will remain spherical with the same curvature, both in magnitude and sign.
B. They will become plane wave fronts.
C. They will become plane wave fronts.
D. They will remain spherical, but with different curvature, both in magnitude and sign.

Answer

To solve the problem regarding the behavior of spherical wavefronts after they strike a plane reflecting surface, we can break it down into the following steps:

### Step 1: Understand the Source of the Wavefront
A point source emits spherical wavefronts. This means that the wavefronts are concentric spheres centered around the point source.

**Hint:** Remember that a point source creates spherical waves that propagate outward in all directions.

### Step 2: Identify the Interaction with the Reflecting Surface
When these spherical wavefronts encounter a plane reflecting surface, they will interact with that surface. The nature of the reflection depends on the characteristics of the wavefronts and the surface.

**Hint:** Consider how light behaves when it hits a flat surface—think about the law of reflection.

### Step 3: Apply the Law of Reflection
According to the law of reflection, the angle of incidence is equal to the angle of reflection. This means that each point on the wavefront that strikes the reflecting surface will reflect back into the medium.

**Hint:** Recall that the angle of incidence equals the angle of reflection for all points on the wavefront.

### Step 4: Determine the Shape of the Reflected Wavefronts
After reflection, the spherical wavefronts will not remain the same. Instead, they will change their curvature. The reflected wavefronts will still be spherical but will have a different curvature compared to the original wavefronts.

**Hint:** Think about how the curvature of a wavefront changes when it reflects off a surface.

### Step 5: Conclusion
The reflected wavefronts will remain spherical but will have a different curvature in terms of both magnitude and sign. Therefore, the correct conclusion is that the wavefronts will continue to be spherical but will differ from the original wavefronts.

**Hint:** Ensure you understand the implications of curvature changes in wavefronts after reflection.

### Final Answer
The spherical wavefronts will remain spherical after reflection but will have a different curvature in both magnitude and sign.