Question

A convex mirror produces an image magnification 1/4. If the object distance is 25 cm find focal length of the mirror

Answer 1

m = - v/u

Since object is always placed in left (negative side), therefore u will be negative.

➵ 1/4 = - v/(- 25)

➵ 25/4 = v

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Mirror Formula

➵ 1/f = 1/v + 1/u

➵ 1/f = 1/(25/4) + 1/(- 25)

➵ 1/f = 4/25 - 1/25

➵ 1/f = 3/25

➵ f = 25/3 or 8.3 cm

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Focal Length is 8.3 cm

Answer 2

Answer:

W = -V/U

step by step explanation :

1 / 4 = - V (-25)

25 / 4 = V

mirror formula

1 /f = 1/v + 1/ u

1 / f = 1/ (25/4) + 1 /(-25)

1 / f = 4/25 - 1 / (-25)

1 / f = 3/25

f= 25 /3 or 8.3 cm....