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JEE Main 2026 (24 Jan, Shift 1) · Optical Instruments & the Eye

Optical Instruments & the Eye question from JEE Main 2026 (24 Jan, Shift 1)

Q5JEE Main 2026 · 24 JAN · SHIFT 1Medium

Optical Instruments & the Eye

In a microscope of tube length 10 cm two convex lenses are arranged with focal length of 2 cm and 5 cm. Total magnification obtained with this system for normal adjustment is $(5)^{k}$ . The value of $k$ is ______.

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Answer: (c)

Normal adjustment: $M = \dfrac{L}{f_o} \cdot \dfrac{D}{f_e}$ with $f_o = 2$ cm, $f_e = 5$ cm.
$M = \dfrac{10}{2} \times \dfrac{25}{5} = 5 \times 5 = 25 = 5^2$ .
So $k = 2$ , answer (c).

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