A thin lens of refractive index 1.60 has R₁ = 40 cm and R₂ = -20 cm in air. Determine its focal length using the lens-maker formula.
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Question

A thin lens of refractive index 1.60 has R₁ = 40 cm and R₂ = -20 cm in air. Determine its focal length using the lens-maker formula.

G1 Physics · Accepted Answer

1/f=(μ−1)(1/R₁−1/R₂), giving f=22.22 cm.