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What is the formula for a lens maker to calculate the focal length of a lens?

1. 1/f = (μ − 1) [1/R1 − 1/R2]
2. The refractive index is 1.5
3. The refractive index is 1.7
4. The refractive index is 1.5

Correct answer: 1/f = (μ − 1) [1/R1 − 1/R2]

Solution

The lens maker's formula is given by 1/f = (μ − 1) [1/R1 − 1/R2], where μ is the refractive index of the lens material, and R1 and R2 are the radii of curvature of the lens surfaces.

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