Question

define the power of lens?Give it's S.l unit. find the power of a concave lens of focal length 2m​

Answer 1

Answer:

The power of the lens is the reciprocal of the focal length of the lens. The SI unit of the power is diopter. ... The power of the convex lens is positive and concave lens is negative. 1 D is the power of the lens whose focal length is 1 meter.

Answer 2

Explanation:

Definition: Power of a lens is defined as the inverse of focal length (in meters) of the lens. It is a measure of the amount of deviation of light ray produced by a lens, more the power, more is the deviation.

SI unit : Unit of power is Dioptre (D).

The power of the lens P= 1/f

Focal length of concave lens f= -2m

P= 1/-2

Then the power of the lens P= -0.5 dioptre

The diopter is the unit of measure for the refractive power of a lens. The power of a lens is defined as the reciprocal of its focal length in metres or P= 1/f where P is the power in dioptres and f is the focal length in metres.

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