The distance between object and its two times magnified real image as produced by a convex lens is 45 cm. The focal length of the lens used is _______ cm. Numerical answer type. Work it out, then open the answer.

Answer: 10. Real image, |m| = 2: v = 2|u| and |u| + v = 45 cm. 3|u| = 45 ⇒ |u| = 15 cm, v = 30 cm 1/f = 1/30 + 1/15 = 3/30 ⇒ f = 10 cm

The distance between object and its two times magnified real image as… | JEE Main 2024 (30 Jan, Shift 1)

Q42JEE Main 2024 · 30 JAN · SHIFT 1Easy

Spherical Surfaces & Thin Lenses

The distance between object and its two times magnified real image as produced by a convex lens is $45\text{ cm}$ . The focal length of the lens used is _______ cm.

Numerical answer type. Work it out, then open the answer.

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Answer: 10

Real image, $|m| = 2$ : $v = 2|u|$ and $|u| + v = 45$ cm.
$3|u| = 45 \Rightarrow |u| = 15\text{ cm}$ , $v = 30\text{ cm}$
$\frac{1}{f} = \frac{1}{30} + \frac{1}{15} = \frac{3}{30} \Rightarrow f = 10\text{ cm}$

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