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
each lens. ​

Answer 1

Answer:

Its unit is dioptre. Explanation: The S.I unit of power is dioptre (symbol D) power of lens = 1/ focal length ( in meter) when focal length is 40 that mean it is positive so therefore the resulting power will also be positive.

Explanation:

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