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For a concave mirror, magnification is +3 (virtual, erect, enlarged). If image is at +60 cm, object is at:
A-20 cm
B-60 cm
C-180 cm
D+20 cm
Answer & Solution
Correct answer: A. -20 cm
1. Magnification m = -v/u, so u = -v/m.
2. u = -(60)/3 = -20 cm.
3. Object is 20 cm in front of the mirror, between P and F.
_Source: NCERT Class 10 Science, Ch 9 "Light Reflection and Refraction", §9.2.4_
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