candlepower unit
Definition
Noun: A candlepower unit is a unit of measurement for luminous intensity, which is the power of light emitted by a source in a particular direction. It is a fundamental photometric quantity.
Usage
The term "candlepower unit" is used in technical and scientific contexts, particularly in physics, engineering, and lighting design, to quantify the brightness of a light source as perceived by the human eye. It is a specific type of measurement unit.
Examples
- The lamp's output was measured at 100 candlepower units.
- Older specifications for spotlights often used candlepower units instead of lumens.
- The photometer was calibrated in standard candlepower units.
Advanced Usage
- Historically, the term "candlepower" was based on the light emitted by a standard candle. Modern standards have replaced it with the candela (cd), which is the SI base unit for luminous intensity. Therefore, "candlepower unit" is often synonymous with the candela in contemporary usage, though "candela" is the preferred term.
- It is used to describe the intensity of focused light sources, such as flashlights, projector lamps, and LED chips, where the directional brightness is more relevant than the total light output.
Variants and Related Words
- Candlepower (n): The luminous intensity expressed in these units. (e.g., "a bulb of high candlepower").
- Candela (cd) (n): The modern SI unit that has officially superseded the candlepower unit. One candela is approximately equal to one historical candlepower unit.
- Luminous intensity (n): The physical quantity that these units measure.
Synonyms
- Luminous intensity unit: A more general descriptive term.
- Candela: The specific, modern equivalent unit.
Related Terms (Not Phrasal Verbs or Idioms)
- Lumen (n): A different unit measuring luminous (total visible light emitted), often confused with candlepower. Candlepower measures intensity in a direction, while lumens measure total light output.
- Foot-candle (n): A unit of (light falling on a surface), which is related to but distinct from luminous intensity.
Noun
-
a measure of luminous intensity
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