An infinitely long rod lies along the axis of a concave mirror of focal length f. The near end of the rod is at distance u > f from the mirror. Its image will have a length -
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Question

An infinitely long rod lies along the axis of a concave mirror of focal length f. The near end of the rod is at distance u > f from the mirror. Its image will have a length -

G1 Physics · Accepted Answer

Derived solution: Step 1: Use the spherical-mirror relation 1/f = 1/v + 1/u with m = - v/u and R = 2f, following the Cartesian sign convention. Step 2: Substitute the values given in the question and apply the geometry/sign convention shown. Step 3: On simplification the result is f²/(u - f). Therefore the correct option is D.

An infinitely long rod lies along the axis of a concave mirror of focal length f. The near end of the rod is at distance u &gt; f from the mirror. Its image will have a length -

An infinitely long rod lies along the axis of a concave mirror of focal length f. The near end of the rod is at distance u > f from the mirror. Its image will have a length -