The SI unit of power of a lens is the dioptre (D).
According to the provided reference, the power of a lens is the reciprocal of its focal length. The standard unit for measuring this power is the dioptre.
Here's a breakdown:
- Power of a lens: A measure of how much a lens converges or diverges light.
- Focal Length: The distance between the lens and the point where parallel rays of light converge (for a converging lens) or appear to diverge from (for a diverging lens).
- Dioptre (D): The SI unit of lens power, defined as the reciprocal of the focal length in meters.
The relationship between power (P) and focal length (f) is:
P = 1 / f (where f is in meters)
For example, if a lens has a focal length of 0.5 meters, its power is:
P = 1 / 0.5 = 2 dioptres
