Which kind of lens can form
an erect image smaller than the object ?

Answer

To determine which kind of lens can form an erect image smaller than the object, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Lens Types**:
- There are two primary types of lenses: convex (or converging) lenses and concave (or diverging) lenses.

2. **Behavior of Concave Lenses**:
- A concave lens diverges light rays that pass through it. When parallel rays of light enter a concave lens, they spread out or diverge.

3. **Image Formation by Concave Lenses**:
- When an object is placed in front of a concave lens, the light rays coming from the object diverge after passing through the lens.
- The brain interprets these diverging rays as coming from a point behind the lens, creating a virtual image.

4. **Characteristics of the Image**:
- The virtual image formed by a concave lens is always erect (upright) and smaller than the actual object.
- This means that the image appears to be smaller than the object, which is what the question is asking.

5. **Conclusion**:
- Therefore, the kind of lens that can form an erect image smaller than the object is a **concave lens**.

### Final Answer:
A concave lens can form an erect image smaller than the object.

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