(astronomy) the magnitude of a star determined using a photometer plus a filter to select light or other radiation of the desired wavelength
noun, Physics. 1. the minimum frequency or maximum wavelength of incident radiation necessary to release photons from a given surface.
noun, Photography. 1. an exposure meter using a photocell for the measurement of light intensity.
noun, Electronics. 1. . [foh-tuh-toob, -tyoob] /ˈfoʊ təˌtub, -ˌtyub/ noun, Electronics. 1. an with a photosensitive cathode, used like a photocell. /ˈfəʊtəʊˌtjuːb/ noun 1. a type of photocell in which radiation falling on a photocathode causes electrons to flow to an anode and thus produce an electric current
[foh-toh-i-lek-tron] /ˌfoʊ toʊ ɪˈlɛk trɒn/ noun, Physics. 1. an emitted from a system by the photoelectric effect. /ˌfəʊtəʊɪˈlɛktrɒn/ noun 1. an electron ejected from an atom, molecule, or solid by an incident photon photoelectron (fō’tō-ĭ-lěk’trŏn’) An electron released or ejected from a photoelectric substance, having absorbed energy from incoming light.