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Focal length of a mirror from the magnification and the object-image distance

This type of question, asked 5 times: 29 Jan 2024, 28 Jan 2025, 4 Apr 2025, 7 Apr 2025, 24 Jan 2026 S2. All 5 questions below, oldest first.

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  1. Question 1

    29 Jan 2024

    98
    If the distance between object and its two times magnified virtual image produced by a curved mirror is 15 cm15\text{ }cm, the focal length of the mirror must be:

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  2. Question 2

    28 Jan 2025

    88
    A concave mirror produces an image of an object such that the distance between the object and image is 20 cm . If the magnification of the image is ' -3 ', then the magnitude of the radius of curvature of the mirror is :

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  3. Question 3

    4 Apr 2025

    23
    Distance between object and its image (magnified by −13- \frac{1}{3} ) is 30 cm . The focal length of the mirror used is (x4)cm\left( \frac{x}{4} \right)cm, where magnitude of value of xx is ____\_\_\_\_.

  4. Question 4

    7 Apr 2025

    84
    A mirror is used to produce an image with magnification of 14\frac{1}{4}. If the distance between object and its image is 40 cm , then the focal length of the mirror is .

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  5. Question 5

    24 Jan 2026 S2

    20
    Distance between an object and three times magnified real image is 40 cm . The focal length of the mirror used is ____\_\_\_\_ cm .

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