Question

two lens have power a) +2D b)-4D . what is the nature and focal length of each lens. ​

Answer 1

Answer:

a). as no is positive it is a convex lens

and focal length is

$\frac{1}{2} = 0.5m$

b). as no is negative it is a concave lens

and focal length is

$\frac{ - 1}{4} = - 0.25m$

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