Light Intensity

To measure light intensity use a handheld digital photometer or download an app on your smartphone.

Light intensity. Hold the photometer in the area that you want to measure the intensity of the light. Luminous intensity a photometric quantity measured in lumens per steradian lm sr or candela cd. Irradiance a radiometric quantity measured in watts per meter squared w m 2. Photometry deals with the measurement of visible light as perceived by human eyes.

Radiant intensity a radiometric quantity measured in watts per steradian w sr. The lumen is evaluated with reference to visual sensation. Intensity physics the name for irradiance used in other branches. For example high intensity discharge lamps emit a high light intensity while fluorescent lamps are considered a cool or low intensity light source.

The fundamental light intensity unit is the candela nominally the light given off by one candle or more precisely a source that emits monochromatic radiation of frequency 540 x 1012 hertz and that has a radiant intensity in that direction of 1 683 watt per steradian. In photometry luminous intensity is a measure of the wavelength weighted power emitted by a light source in a particular direction per unit solid angle based on the luminosity function a standardized model of the sensitivity of the human eye the si unit of luminous intensity is the candela cd an si base unit. Light intensity luminous intensity measured in candelas candlepower intensity intensity level strength the amount of energy transmitted. Light intensity synonyms light intensity pronunciation light intensity translation english dictionary definition of light intensity.

Remember that most office spaces are comfortably lit around 250 500 lux and supermarkets or work spaces that require detailed work are lit around 750 1 000 lux. Several measures of light are commonly known as intensity.