Question

Find the power of a lens of focal length 20cm.​

Answer 1

Answer:

Power of lens is 100/f in metres

=100/20

=5D

is your answer

Answer 2

The power of a lens of focal length 20cm is 5D.

Explanation:

• F = 20cm

           = 0.2m

• Power of convergence is given by

           p = 1/f

          So, p = 1/0.2

                   = 5D

          Since p1 = p2.

• So both lenses have same convergence of refracted light.
• 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 meters or D = 1/f.
• Where D is the power in diopters and f is the focal length in meters.
• Lens surface power can be found with the index of refraction and radius of curvature.

To Learn More...

1.The power of a convex lens of focal length 20cm in diopter unit is

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