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Lens formula with a convex lens

This type of question, asked 3 times: 2023, 2025, 2026. All 5 questions below, oldest first.

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  1. Question 1

    2023

    30 (B)
    An object of height 10 cm is placed 25 cm away from the optical centre of a converging lens of focal length 15 cm. Calculate the image-distance and height of the image formed.

  2. Question 2

    2025

    31
    A convex lens forms an 8⋅08{\cdot}0 cm long image of a 2⋅02{\cdot}0 cm long object which is kept at a distance of 6⋅06{\cdot}0 cm from the optical centre of the lens. If the object and the image are on the same side of the lens, find (i) the nature of the image, (ii) the position of the image, and (iii) the focal length of the lens.

  3. Question 3

    2025

    10
    To get an image of magnification −1-1 on a screen using a lens of focal length 20 cm, the object distance must be :

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  4. Question 4

    2026

    35
    (a) Write the expression for the magnification produced by a lens in terms of object distance and image distance. (b) A 4 cm tall object is placed perpendicular to the principal axis of a convex lens of focal length 20 cm. Calculate the size of the image formed, if the distance of the object from the lens is 10 cm.

  5. Question 5

    2026

    33
    The given figure shows image formation by a lens. Analyse the figure and answer the following questions : (a) What is the type of lens used for image formation in the given ray diagram ? (b) If the real image is formed at a distance of 30 cm from the lens and the size of image is twice the size of the object, then where was the object placed ?