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A 10-cm-tall object placed 30 cm in front of a 20-cm concave mirror has an image at:
A+30 cm, erect
B+60 cm, virtual
C-15 cm, inverted (option)
D-60 cm, inverted, real
Answer & Solution
Correct answer: D. -60 cm, inverted, real
1. Apply 1/v + 1/u = 1/f with u = -30, f = -20.
2. 1/v = -1/20 + 1/30 = -3/60 + 2/60 = -1/60, so v = -60 cm.
3. Image is 60 cm in front (real), inverted (because v and u have same sign).
_Source: NCERT Class 10 Science, Ch 10 "The Human Eye and the Colourful World", §10.1_
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