Question

What is meant by power of a lens? Write its SI unit. A student uses a lens of focal
length 40 cm and another of –20 cm. Write the nature and power of each lens.
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Answer 1

Answer:

The deviation of the incident light rays produced by a lens on refraction through it, is a measure of its power. when focal length is 40 that mean it is positive so therefore the resulting power will also be positive. If the power is positive it considered as power of convex lens.

Explanation:

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Answer 2

The degree of convergence or divergence achieved by a lens is called the power of a lens. Its SI unit is dioptre.

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