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Answer the following. (Class 10 Science 2023, Q30)

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ScienceCBSE Class 10 · Board exam 2023, set 31/1/1 · 3 marks · Short answer

CBSE Class 10 Science 2023: question 30

Set in the CBSE Class 10 board exam of 2023, paper 31/1/1, section C, question 30, for 3 marks. Try it first; the hints and our step-by-step solution are below.

Q30 · 3 marks · Short answerLight – Reflection and Refraction

Answer the following.

  1. (a)

    Complete the following ray diagram to show the formation of image :

    0 marks
  2. (b)

    Mention the nature, position and size of the image formed in this case.

    0 marks
  3. (c)

    State the sign of the image distance in this case using the Cartesian sign convention.

    0 marks

Figure in the paper: A convex-type mirror surface (hatched on the right side) with pole P on the principal axis; object AB upright on the axis at left (B on axis, A at top). Points R and C on the axis to the right of P, behind the mirror (R nearer, C farther). Ray 1 goes horizontally from A to the mirror. Ray 2 goes from A to the mirror and its reflected continuation is a dashed line heading toward C. Labelled: Ray 1, Ray 2, A, B, P, R, C, Object. See it in the official paper.

Source: official question paper from cbse.gov.in (PDF). See it in the full 2023 board paper, set 31/1/1.

Hints

Open one hint at a time and try again before the next.

Hint 1

F and C lie behind the mirror, so it is a convex mirror. Where does a ray parallel to the axis appear to come from after reflection?

Hint 2

A ray aimed at the centre of curvature hits the mirror normally. Use the meeting point of the backward extensions to find the image.

Step-by-step solution

Each step shows the marks it earns, as an examiner would award them. Checked by an independent re-solve from the question paper.

  1. (a) The mirror is a convex mirror: its reflecting surface faces the object, and F and C lie behind it. The point marked R on the axis is the principal focus F.

    • Ray 1 (parallel to the principal axis) is reflected so that it appears to come from F behind the mirror. Draw it diverging outward, with a dotted line back to F.
    • Ray 2 (directed towards C) strikes the mirror normally, so it is reflected back along the same path.
    • Extend both reflected rays backwards as dotted lines. They meet behind the mirror at A′.
    • Drop a perpendicular from A′ to the axis to get B′. A′B′ is the image. It lies between P and F.
    1 mark

  2. (b) Nature: virtual and erect.

    ½ mark

  3. Position: behind the mirror, between P and F.

    ½ mark

  4. Size: diminished (smaller than the object).

    ½ mark

  5. (c) The image is formed behind the mirror, on the side opposite the object. By the Cartesian sign convention, the image distance is positive.

    ½ mark

Answer: (a) Image A′B′ is formed behind the mirror between P and F; (b) virtual, erect, behind the mirror between P and F, diminished; (c) positive.

Where the marks are

  • Completes the ray diagram correctly with reflected rays and image A′B′ located (1 mark)
  • Virtual and erect (½ mark)
  • Position behind the mirror between P and F (½ mark)
  • Diminished (½ mark)
  • Image distance positive (½ mark)

Revise the chapter

Practise this chapterBoard-style questions from Light – Reflection and Refraction, one at a time, marked against the answer key and marking points.Back to the full paper2023 board paper, set 31/1/1: every question, by section.

The question is transcribed from the official paper; figures are described in words. The solution, hints and chapter tag are ours. Spotted an error? Write tosupport@questionbuddy.in.