A person can see objects only at a distance greater than 40 cm. He is advised to use lens of power
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Question

A person can see objects only at a distance greater than 40 cm. He is advised to use lens of power

G1 Physics · Accepted Answer

Derived solution: Step 1: Use the thin-lens formula 1/f = 1/v - 1/u with m = v/u. For lens material/medium changes use the lens-maker relation with the relative refractive index; powers of thin lenses in contact add. Step 2: Substitute the values given in the question and apply the geometry/sign convention shown. Step 3: On simplification the result is + 1.5 D. Therefore the correct option is B.