Two thin lenses are of same focal lengths ( f ), but one is convex and the other one is concave. When they are placed in contact with each other, the - Physics MCQ NEET 2023 2026 | ExamTest.live

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Two thin lenses are of same focal lengths (f), but one is convex and the other one is concave. When they are placed in contact with each other, the equivalent focal length of the combination will be:

Solution & Step-by-step Explanation

The focal length of a convex lens is + f and for a concave lens is - f .The equivalent power P_{e q} is: P_{e q} = P_{1} + P_{2} = \frac{1}{f} + (- \frac{1}{f}) = 0 Equivalent focal length F_{e q} = \frac{1}{P _{e q}} = \frac{1}{0} = \infty .

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Two thin lenses are of same focal lengths (f), but one is convex and the other one is concave. When they are placed in contact with each other, the equivalent focal length of the combination will be:

Zero

\frac{f}{4}

\frac{f}{2}

Infinite

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