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An object placed at 5 cm in front of a concave mirror (R = 15 cm; f = −7.5 cm) forms an image that is:
AReal, inverted, between mirror and focus
BVirtual, erect, magnified, behind the mirror at 15 cm
CAt infinity
DReal, inverted at 5 cm
Answer & Solution
Correct answer: B. Virtual, erect, magnified, behind the mirror at 15 cm
f = −7.5 cm; u = −5 cm (object inside the focal length). 1/v = 1/(−7.5) − 1/(−5) = −0.1333 + 0.2 = +0.0667 → **v = +15 cm** (behind mirror → virtual). m = −15/(−5) = **+3** → erect, magnified 3×, virtual. Concave mirror acts as a magnifying glass when object is inside focal length.
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