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| Photogalvanic processes
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The production of electrical current from light. |
| Photogammetry
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Photography that is used to take accurate measurements, as with aerial photographs which are used in surveying, etc. |
| Photon
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A particle of light that acts as an individual unit of energy. |
| Photoperiodism
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The response of plants to the length of a day and night (i.e. poinsettias, cactus, night blooming flowers). |
| Photosynthesis
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The internal process by which a plant turns sunlight into growing energy. The formation of carbohydrates in plants from water and carbon dioxide, by the action of sunlight on the Chlorophyll within the leaves. |
| Photovoltaic
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The process of converting light directly into electricity using specially designed silicon cells. Solar power systems utilize this method. |
| Photovoltaic cell
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The specially designed silicon cell, which generates an electrical current when light, is directed onto it. Solar power systems utilize this method. |
| Photovoltaic device
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A solid-state electrical device that converts light directly into direct current electricity of voltage-current characteristics that are a function of the characteristics of the light source and the materials in and design of the device. Solar photovoltaic devices are made of various semi-conductor materials including silicon, cadmium sulfide, cadmium telluride, and gallium arsenide, and in single crystalline, multi-crystalline, or amorphous forms. |
| Photovoltaic-thermal (pv/t) systems
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A solar energy system that produces electricity with a PV module, and collects thermal energy from the module for heating. There are no commercially available systems available (as of 11/97). |
| Phyllode
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A leaf stalk expanded to look like and act like a leaf. |
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