How is a wavefront related to the direction of corresponding rays ?

Answer

To understand how a wavefront is related to the direction of corresponding rays, we can break down the explanation into several steps:

### Step-by-Step Solution:

1. **Definition of Wavefront**: A wavefront is defined as the surface over which an oscillation (such as a wave) has a constant phase. In simpler terms, it is the imaginary surface that connects all points that are in the same phase of the wave.

2. **Definition of Rays**: Rays are lines that represent the direction of energy propagation in a wave. They are drawn perpendicular to the wavefronts and indicate the path along which the wave travels.

3. **Relationship Between Wavefront and Rays**: The key relationship between wavefronts and rays is that rays are always perpendicular to the wavefronts. This means that if you have a wavefront, the rays that correspond to that wavefront will always make a right angle (90 degrees) with it.

4. **Visualizing the Concept**: Imagine a series of wavefronts moving outward from a point source. Each wavefront is a circle (in the case of spherical waves) or a straight line (in the case of plane waves). The rays would be drawn radiating outward from the center of the wavefronts, and they would intersect the wavefronts at right angles.

5. **Conclusion**: Therefore, we can conclude that the direction of the rays is always perpendicular to the wavefronts. This relationship is fundamental in understanding wave propagation and is applicable in various contexts, such as optics and acoustics.

### Final Answer:
The wavefront is related to the direction of corresponding rays in that the rays are always perpendicular to the wavefronts.

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