Physics · 2013
JEE Main · 22 April 2013, Shift 1 · Q24
The image of an illuminated square is obtained on a screen with the help of a converging lens. The distance of the square from the lens is 40 cm. The…
The image of an illuminated square is obtained on a screen with the help of a converging lens. The distance of the square from the lens is $\displaystyle 40$ cm. The area of the image is $\displaystyle 9$ times that of the square. The focal length of the lens is :
Official answer
(4)
$\displaystyle 30$ cm
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JEE Main 2013 Physics question, with the answer from NTA’s final answer key. Where our answers come from.