JEE Mains · Physics · STD 12 - Ray optics and optical instruments
- JEE Mains 2023
- Hard
- Numerical
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 \(............cm\).

Pick an option to check your answer.
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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