The mirror used by dentists to concentrate light on the tooth to be examined is a ______ mirror.

Options

A. concave
B. plane or concave
C. convex
D. plane

Answer

To solve the question, "The mirror used by dentists to concentrate light on the tooth to be examined is a ______ mirror," we need to analyze the types of mirrors and their properties.

### Step-by-Step Solution:

1. **Understanding the Types of Mirrors**:
- There are three main types of mirrors: concave, convex, and plane.
- Each type has different properties regarding image formation and light concentration.

2. **Concave Mirror**:
- A concave mirror is curved inward, resembling a bowl.
- It can focus light rays that are parallel to its principal axis to a single point (the focus).
- When an object is placed close to the mirror (between the focus and the mirror), it produces a virtual image that is upright and enlarged.

3. **Application in Dentistry**:
- Dentists use concave mirrors to examine teeth because they need to see a magnified view of the tooth.
- The concave mirror allows the dentist to concentrate light on the tooth, making it easier to identify cavities or other issues.

4. **Comparison with Other Mirrors**:
- **Plane Mirror**: Produces images that are the same size as the object, without magnification. This is not suitable for detailed examination.
- **Convex Mirror**: Always produces diminished images, which are smaller than the object. This is also not suitable for detailed examination.

5. **Conclusion**:
- Since the concave mirror provides an enlarged, upright, and virtual image, it is the correct choice for dentists to use when examining teeth.

### Final Answer:
The mirror used by dentists to concentrate light on the tooth to be examined is a **concave mirror**.

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