A boy is trying to start a fire by focusing sunlight on a piece of paper using an equiconvex lens of focal length 10 cm . The diameter of the sun is 1.39 × 1 0 9 m and its mean distance from the earth

Question

A boy is trying to start a fire by focusing sunlight on a piece of paper using an equiconvex lens of focal length 10 cm . The diameter of the sun is 1.39 × 1 0 9 m and its mean distance from the earth is 1.5 × 1 0 11 m . What is the diameter of the sun's image on the paper?

TestHub · Accepted Answer

From the relation O I ​ = u v ​ Here, O = 1.39 × 1 0 9 , v = 0.1 m , u ∴ I ​ = 1.5 × 1 0 11 m = 1.5 × 1 0 11 0.1 ​ × 1.39 × 1 0 9 = 9.2 × 1 0 − 4 m ​

Physics - Geometrical Optics Question with Solution | TestHub

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