# If the numerical value of the power of this lens is 10 D, what is its focal length in the Cartesian system ? - Science

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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