Calculate the focal length of a corrective lens having power +2D.

Data: Power of a lens = + 2D
To find: Its focal length. (f)

Solution: P = 1 / f(m)

Where: P = Power and f = Focal length of lens in metre)

Therefore, f = 1/P

Therefore, f = + (1/2) metre

Therefore, f = + 0.5 metre.

Ans. The focal length of the given lens is + 50 cm.

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