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प्रश्न
The power of a lens is +2.0 D. Find its focal length and state the kind of lens.
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उत्तर
P = + 2.0 D
P = `1/("F" ("in meter"))`
`=> "F" = 1/ "P" = 1/2`
F = 0.5 m or 50 cm
∵ Power is (+ve)
∴ It is a convex lens.
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