In which case will the angle of incidence be equal to the angle of refraction?

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question:**
We need to determine the condition under which the angle of incidence (i) is equal to the angle of refraction (r).

2. **Identify the Relevant Law:**
The relationship between the angle of incidence and the angle of refraction is described by Snell's Law, which states:
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