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TS EAMCET · Physics · Ray Optics

An object is placed at a certain distance left to a convex lens of focal length \(20 \mathrm{~cm}\). Find the distance of the object if the image obtained is magnified by 4 times.

  1. A \(25 \mathrm{~cm}\) when the image is real
  2. B \(15 \mathrm{~cm}\) when the image is real
  3. C \(25 \mathrm{~cm}\) when the image is virtual
  4. D \(10 \mathrm{~cm}\) when the image is virtual
Verified Solution

Answer & Solution

Correct Answer

(A) \(25 \mathrm{~cm}\) when the image is real

Step-by-step Solution

Detailed explanation

For a lens, Magnification \(=\frac{\text { Size of image }}{\text { Size of object }}=\frac{v}{u}\) \(\Rightarrow \quad m=\frac{I}{O}=\frac{v}{u}\) Here, \(m= \pm 4\) For \(m=-4,-4=\frac{v}{u} \Rightarrow v=-4 u\) Now by lens formula,…
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