Which of the following mirrors is used to concentrate light on a given spot?

Options

A. Concave mirror
B. Convex mirror
C. Plane mirror
D. None of these

Answer

To determine which mirror is used to concentrate light on a given spot, we can analyze the properties of different types of mirrors.

### Step-by-Step Solution:

1. **Understanding Mirror Types**:
- There are three types of mirrors we need to consider: concave mirrors, convex mirrors, and plane mirrors.

2. **Analyzing the Concave Mirror**:
- A concave mirror is shaped like a bowl. When parallel rays of light strike a concave mirror, they converge (come together) at a point known as the focus.
- Therefore, a concave mirror can concentrate light on a specific spot.

3. **Analyzing the Convex Mirror**:
- A convex mirror is curved outward. When parallel rays of light hit a convex mirror, they appear to diverge from a point behind the mirror (the focus).
- This means that a convex mirror does not concentrate light; instead, it spreads it out.

4. **Analyzing the Plane Mirror**:
- A plane mirror has a flat surface. When light rays strike a plane mirror, they reflect in a straight line without converging or diverging.
- Thus, a plane mirror neither concentrates nor diverges light.

5. **Conclusion**:
- Based on the analysis, the only mirror that can concentrate light on a given spot is the **concave mirror**.

### Final Answer:
The mirror used to concentrate light on a given spot is the **concave mirror**.

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