When a wave undergoes reflection at a denser medium, what happens to its phase ?

Explanation

To determine what happens to the phase of a wave when it undergoes reflection at a denser medium, we can follow these steps:

### Step 1: Understanding Wave Reflection
When a wave travels from a rarer medium (like air) to a denser medium (like water or glass), it reaches the boundary between the two media. At this boundary, some of the wave is reflected back into the rarer medium.

**Hint:** Consider the properties of the media involved and how they affect wave behavior.

### Step 2: Analyzing the Incident Wave
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