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Science — CBSE Class 10 board question

Q1. [5]
Answer the following :
  1. (i) A student wishes to study the image formation by a concave mirror using candle flame as object. State the type of the image formed by the mirror and mention the change in the image formed, if any, that he observes when the candle flame is gradually moved away from the pole of the mirror. Draw a ray diagram to show the image formation when the object distance is nearly equal to the radius of curvature of the mirror. [3]
  2. (ii) A convex mirror used for rear-view on an automobile has a focal length of 3·0 m. If a bus is located at 6·0 m from this mirror, use mirror formula to find the position of the image of the bus as seen in the mirror. [2]
Previously asked in CBSE board exam
2025 31/3/1 Q36(b)
Generated by claude-sonnet-4-6 · 2026-06-15 06:49 · grounding rag
Model Answer

(i)

Type of image: When the object (candle) is between the pole and focus, the image formed by a concave mirror is virtual, erect, and enlarged.

Change as candle moves away from pole:

Ray diagram (object at C, i.e., u ≈ R):

```
C F P
←————|————|————|
\ /|
\/ |
Object ↑ ↑ Image (at C, same size, real, inverted)
```
(Two rays: one parallel to principal axis reflects through F; one through C reflects back on itself — image forms at C, real, inverted, same size.)

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(ii)

Given: f = +3.0 m (convex mirror), u = –6.0 m

Mirror formula: $\dfrac{1}{v} + \dfrac{1}{u} = \dfrac{1}{f}$

$$\frac{1}{v} = \frac{1}{f} - \frac{1}{u} = \frac{1}{3} - \frac{1}{-6} = \frac{1}{3} + \frac{1}{6} = \frac{3}{6} = \frac{1}{2}$$

$$v = +2 \text{ m}$$

The image is formed 2 m behind the mirror; it is virtual and erect.

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Explanation
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Previous-year CBSE Grade 10 board exam questions, organised by subject and chapter, each with a model answer — free to read and print.