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. In other contexts, it refers to optical power, the ability of a lens or other optical device to focus light. It is measured in dioptres (inverse metres), and equals the inverse of the focal length of the optical device.
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Famous quotes containing the word power:
“I, who cannot stay in my chamber for a single day without acquiring some rust,... confess that I am astonished at the power of endurance, to say nothing of the moral insensibility, of my neighbors who confine themselves to shops and offices the whole day for weeks and months, aye, and years almost together. I know not what manner of stuff they are of,—sitting there now at three o’clock in the afternoon, as if it were three o’clock in the morning.”
—Henry David Thoreau (1817–1862)