JEE Mains · Physics · STD 12 - 9. Ray optics and optical instruments
If the distance between object and its two times magnified virtual image produced by a curved mirror is \(15 \mathrm{~cm}\), the focal length of the mirror must be _______.
- A \(15 \mathrm{~cm}\)
- B \(-12 \mathrm{~cm}\)
- C \(-10 \mathrm{~cm}\)
- D \(10 / 3 \mathrm{~cm}\)
Answer & Solution
Correct Answer
(C) \(-10 \mathrm{~cm}\)
Step-by-step Solution
Detailed explanation
\( \mathrm{m}=2=\frac{-\mathrm{v}}{\mathrm{u}} \) \( 2=\frac{-(15-\mathrm{u})}{-\mathrm{u}} \) \( 2 \mathrm{u}=15-\mathrm{u} \) \( 3 \mathrm{u}=15 \Rightarrow \mathrm{u}=5 \mathrm{~cm} \) \( \mathrm{v}=15-\mathrm{u}=15-5=10 \mathrm{~cm} \)…
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