Question

13. What is called power of lense ? State the SI unit of power of lense and write the
formula relating the power of lens and focal length of the lense.
Please give answer for (3 marks)
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Answer 1

Answer:

Power of lens is known as the inverse of the focal length of the lens measured in meter(m). Power of lense = 1/ focal length in meter. The lense used is a convex lens because the focal length is a positive value.

Power of lens is the ability of the lens to converge the rays of light falling on it. It can also be defined as P=1/f where f is the focal length. S.I. unit of power is D(Dioptre).

The watt (symbol: W) is a unit of power. In the International System of Units (SI) it is defined as a derived unit of 1 joule per second, and is used to quantify the rate of energy transfer.