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A convex lens of focal length 20 cm forms a real, inverted image of an object placed at 30 cm in front of it. The image distance v and magnification are:
Av = 60 cm, m = −2 (inverted, magnified)
Bv = 12 cm, m = +0.4 (erect, diminished)
Cv = −60 cm, m = +2 (virtual)
Dv = 20 cm, m = −1
Answer & Solution
Correct answer: A. v = 60 cm, m = −2 (inverted, magnified)
Convex lens: f = +20 cm. u = −30 cm. 1/v − 1/u = 1/f → 1/v = 1/20 + (−1/30) = 3/60 − 2/60 = 1/60 → **v = +60 cm** (real image, opposite side). m = v/u = 60/(−30) = **−2** (inverted, 2× magnified).
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