Correct Answer - Option 4 : Dioptre
The correct answer is Dioptre.
CONCEPT:
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Power is the ability to bend light and it is equal to the reciprocal of the focal length of the lens/mirror in meters.
Power (P) = 1/f
Where f is the focal length of the lens/mirror.
EXPLANATION:
- The SI unit of the focal length is the meter (m).
So the SI unit of power = 1/(SI unit of focal length) = m-1 = Dioptre (D)
1 m-1 = 1 D
- Watt is the SI unit of power for energy consumption.
- The SI unit of the power of a lens is given by Dioptre.
- Candela is the SI unit for the luminous intensity of an object.
- Centimeter measures the distance.
- SI unit of distance is metre.