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Question
The power of a lens is + 1.0 D is :
Options
convex of focal length 1.0 cm
convex of focal length 1.0 m
concave of focal length 1.0 cm
concave of focal length 1.0 m
Solution
Power of a lens is +1.0 D. The positive sign indicates that the focal length of the lens is positive which indicates the lens is a convex lens.
Power is P = `1/("f" ("in" "m"))`
+ 1.0 D = `1/("f" ("in" "m"))`
∴ f = 1.0 m
Hence, the correct answer is convex of focal length 1.0 m.
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