Question

find the focal length of the mirror. the object is kept at a distance of 27 cm from mirror and two times magnified image is formed on the screen. what is the type of mirror used
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Answer 1

Answer:

Explanation:

$u = -27 cm\\v = 2u = 2*(-27) = -54 cm\\f = ?$

$1/f = 1/v + 1/u \\1/f = 1/(-54) + 1/(-27)\\1/f = (-1 - 2)/54\\1/f = -3/54\\\\f = -54/3 = -18 cm$

∴ f = -18 cm