Question

Distance equivalent to half of radius of curvature of mirror from its pole.​

Answer 1

The distance from the pole to the focus is still the focal length (f), but now it's also negative. With two sign switches, the rule that focal length is half the radius of curvature is still true in the same approximate way as before.

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introduction.

f ≈r2

Answer 2

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The distance from the pole to the focus is still the focal length (f), but now it's also negative. With two sign switches, the rule that focal length is half the radius of curvature is still true in the same approximate way as before.