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Per NCERT Example 9.3, a concave lens (f = −15 cm) forms an image at v = −10 cm. What is the object distance u?
A−10 cm
B+30 cm
C−30 cm
D+10 cm
Answer & Solution
Correct answer: C. −30 cm
Per NCERT Example 9.3, using lens formula: 1/u = 1/v − 1/f = 1/(−10) − 1/(−15) = (−3+2)/30 = −1/30 → u = −30 cm.
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