A person looks into the mirror by placing it close to his face. The image of his face was erect, laterally inverted and of the same size. Then, the mirror must be

Options

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

Answer

To determine the type of mirror that produces an erect, laterally inverted image of the same size when a person looks into it closely, we can analyze the properties of different types of mirrors.

### Step-by-Step Solution:

1. **Identify the Properties of the Image**:
- The image is **erect**: This means the image appears upright.
- The image is **laterally inverted**: This means the left and right sides of the image are reversed.
- The image is of the **same size**: This indicates that the magnification is 1.

2. **Consider the Types of Mirrors**:
- The three common types of mirrors are **plane mirrors**, **concave mirrors**, and **convex mirrors**.

3. **Analyze Plane Mirrors**:
- Plane mirrors produce images that are:
- Erect (the same orientation as the object).
- Laterally inverted (left becomes right).
- The same size as the object (magnification = 1).
- Since all three properties match, a plane mirror is a suitable candidate.

4. **Analyze Concave Mirrors**:
- Concave mirrors can produce erect images, but only when the object is placed between the focal point (F) and the mirror.
- In this case, the image produced is **magnified** (larger than the object), which does not match the requirement of being the same size.
- Therefore, a concave mirror is not suitable.

5. **Analyze Convex Mirrors**:
- Convex mirrors always produce images that are:
- Erect.
- Diminished (smaller than the object).
- Since the image is not the same size, a convex mirror cannot be the answer.

6. **Conclusion**:
- The only type of mirror that satisfies all the conditions (erect, laterally inverted, and same size) is the **plane mirror**.

### Final Answer:
The mirror must be a **plane mirror**.