Power (physics)
From Simple English Wikipedia, the free encyclopedia
In physics, power (symbol: P) is the rate at which work is performed or energy is transferred. In the SI system of measurement, power is measured in watts (symbol: W).
As a rate of change of work done or the energy of a subsystem, power is:
where
[edit] Power in optics
In optics, or radiometry, the term power sometimes refers to radiant flux, the average rate of energy transport by electromagnetic radiation, measured in watts. But the term "power" is also used to express the ability of a lens or other optical device to focus light. It is measured in dioptres (inverse metres), and is equal to one over the focal length of the optical device.
