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The power of a concave lens is -2.5 diop...

The power of a concave lens is -2.5 dioptres. Find it focal length.
Calculate the focal length of a corrective lens having power +2.5 D.

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Verified by Experts

Data : Convex lens , `P=-2.5 D , f=? `
`P=1/f therefore -2.5 D=1/f`
`f=-1/(2.5D) = -0.4 m =-40cm`
The focal length of the lens = -40cm.
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