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Science — CBSE Class 10 board question

Q1. [3]
A convex lens can form a (i) real, inverted and magnified image as well as (ii) virtual, erect and magnified image of an object. If the focal length of the lens is 10 cm, what should be the range of the object distance in both cases ? Draw ray diagrams to justify your answer.
Previously asked in CBSE board exam
2023 31/5/1 Q30 (b)
Generated by claude-sonnet-4-6 · 2026-06-15 06:50 · grounding rag
Model Answer

Case (i): Real, inverted and magnified image
For a convex lens to form a real, inverted and magnified image, the object must be placed between F and 2F, i.e., object distance $u$ must satisfy:
$$f < |u| < 2f \implies 10 \text{ cm} < |u| < 20 \text{ cm}$$

Ray Diagram (i):
(Object between F and 2F; image forms beyond 2F on the other side — real, inverted, magnified)

```
|
O | I
↑ F 2F 2F' ↑↑
---●--●----●-----●----●---
|
```

---

Case (ii): Virtual, erect and magnified image
For a virtual, erect and magnified image, the object must be placed between the optical centre and F, i.e.:
$$0 < |u| < f \implies 0 < |u| < 10 \text{ cm}$$

Ray Diagram (ii):
(Object between O and F; image forms on the same side as object — virtual, erect, magnified)

```
|
I↑↑ | O↑
F
---●--●--●-----------
|
```

Source: Chapter 9, Section 9.3.5 – Image Formation in Lenses Using Ray Diagrams

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Explanation
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