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Per NCERT, if a lens has POWER = +2.0 D, what is its FOCAL LENGTH — and is it convex or concave?
Af = +0.50 m (= 1/P); positive power and positive f indicate it is a CONVEX lens
Bf = +2.0 m; concave
Cf = −0.50 m; convex
Df = +50 m; concave
Answer & Solution
Correct answer: A. f = +0.50 m (= 1/P); positive power and positive f indicate it is a CONVEX lens
Per NCERT §9.3.8, f = 1/P = 1/2 = +0.50 m. Positive → convex.
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