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If the image formed by a convex mirror of focal length 30 cm is a quarter of the size

If the image formed by a convex mirror of focal length 30 cm is a quarter of the size of the object, then the distance of the object from the mirror will be

Options

(a) 30 cm
(b) 60 cm
(c) 90 cm
(d) 120 cm

Correct Answer:

90 cm

Explanation:

Given, f = + 30 cm and m = 1 / 4 Magnification, m = f / (f – u)

Therefore, 30 / (30 – u) = 1 / 4

30 – u = 120

⇒ u = -90 cm

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