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Question
If the numerical value of the power of this lens is 10 D, what is its focal length in the Cartesian system ?
Solution
Since, power of a lens is given by the relation
`P=1/f` (in metres)
p = 10 D (given)
`10 = 1/f`
`f = 1/10`
`f= 0.1 m`
Therefore, the focal length of the lens is 0.1 m as the lens is concave in nature.
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