JEE Mains · Physics · STD 12 - 9. Ray optics and optical instruments
An object is placed on the principal axis of convex lens of focal length \(10\,cm\) as shown. A plane mirror is placed on the other side of lens at a distance of \(20\,cm\). The image produced by the plane mirror is \(5\,cm\) inside the mirror. The distance of the object from the lens is \(............cm\).
- A \(28\)
- B \(30\)
- C \(29\)
- D \(3.2\)
Answer & Solution
Correct Answer
(B) \(30\)
Step-by-step Solution
Detailed explanation
\(f =10\,cm\) \(\frac{1}{ v }-\frac{1}{ u }=\frac{1}{ f }\) \(\frac{1}{15}-\frac{1}{- u }=\frac{1}{10}\) \(\Rightarrow \frac{1}{ u }=\frac{1}{10}-\frac{1}{15}\) On solving we get value of \(u\) as \(30\,cm\).
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