## Frequently Use LED-Related Terminology:

1) | A lumen is a unit of standard measurement used to describe how much light is contained in a certain area. |

2) | A lumen is defined as one candela multiplied by one steradian, which can be expressed as: 1(lm) = 1(cd) x 1(sr). A related unit of measurement — although not part of the standard units — is the foot-candle, |

3) | The higher the number, the more light is emitted. |

1) | Measures energy required to light the product. |

2) | The watt is defined as “the power which in one second gives rise to energy of 1 joule”. In mechanical terms, a power of 1 watt can, in 1 second, move a mass of 1 kilogram through a distance of 1 meter with such force that the kilogram’s velocity at the end of the meter will be 1 meter per second greater than it was at the beginning. In an electric circuit, 1 watt is a current of 1 ampere at a pressure of 1 volt. |

3) | The lower the wattage, the less energy used. |

1) | In lighting design, “efficacy” refers to the amount of light (luminous flux) produced by a light source, usually measured in lumens, as a ratio of the amount of power consumed to produce it, usually measured in watts. |

2) | This is not to be confused with efficiency which is always a dimensionless ratio of output divided by input which for lighting relates to the watts of visible power as a fraction of the power consumed in watts. |

3) | The higher the number, the more efficient the product. |

1) | Color rendition is the effect of the lamp’s light spectrum on the color appearance of objects. |

2) | Scale of 0 to 100, used by manufacturers of fluorescent, metal halide and other nonincandescent lighting equipment to describe the visual effect of the light on colored surfaces. Natural daylight and any light source approximating a blackbody source is assigned a color rendering index (CRI) of 100. |

1) | Color Temperature of a light source is defined by its warmth or coolness and is expressed in degrees Kelvin. |

2) | Color temperatures over 5,000K are called cool colors (blueish white), |

3) | Lower color temperatures (2,700–3,000 K) are called warm colors (yellowish white through red) |