Luxmeter measures luminous intensity. The SI unit of luminous intensity is candela (cd).
In physics, intensity is a measure of the time-averaged energy flux. The word "intensity" here is not synonymous with "strength", "amplitude", or "level", as it sometimes is in colloquial speech. For example, "the intensity of pressure" is meaningless, since the parameters of those variables do not match.
A lumen is a unit of luminous flux, which is the amount of light emitted per unit time. A watt is a unit of power (such as electrical power), which is the amount of energy consumed per unit time. Light bulbs have ratings in watts, which measures how much electricity they use, and lumens, which measures how much light they give off. For the same kind of bulb (incandescent, fluorescent, LED, etc.), a bulb with a higher wattage will produce more lumens. However, a 10-watt LED or compact fluorescent bulb may produce more lumens than a 40-watt incandescent bulb.
Yes, flux will corrode the bottom of your fire brick forge.
because the flux capacitor allows it to float on air
It will happen in any magnetic field if the iron rod is aligned with the external flux lines and you hammer in the direction of the flux lines, and you have LOTS of patience as you may need to hammer a hundred or more times to get a "strong" magnetization. What happens (if you want to know) is the hammering joggles the magnetic domains from their previous random orientations and they gradually settle into orientations more closely aligned with the external flux lines. The same thing will happen but more effectively if the iron rod is heated to its curie point temperature and then cooled while aligned with the external flux lines. The heat allows all the magnetic domains to realign.
The candela measures luminous intensity, whereas the lumen measures luminous flux. In simple terms, you can think of luminous intensity as being similar to 'brightness', while luminous flux is similar to the rate at which light leaves its source.
Illuminance is another term for luminous-flux density which defines the intensity of the luminous flux arriving at a surface, measured in lumens per square metre, which is given the special name 'lux'.
Illuminance is another term for luminous-flux density which defines the intensity of the luminous flux arriving at a surface, measured in lumens per square metre, which is given the special name 'lux'.
Luminous flux is measured in lumens (symbol: lm).
Many devices can measure magnetic flux: Hall effect sensors, fluxgates, magnetoresistive devices, etc.
lumen
Not directly, as you are comparing apples with oranges in two senses: (a) a lumen is an SI unit, whereas a candlepower is an Imperial unit, and (b) lumens are used to measure luminous flux, whereas candlepower is used to measure luminous intensity.
Illuminance is another word for 'luminous-flux density', which describes the intensity of the luminous flux hitting a surface. Its SI unit of measurement is the lux, which is a special name given to a lumen per square metre. Luminance is a measure of the intensity of the light reflected by a surface. Its SI unit of measurement is the candela per square metre.
Candela (cd).
The 3 measurable quantities of light are:* Luminous intensity-- which refers to the brightness of a light source* Luminous flux-- is the rate at which light is emitted from a source and strikes the surface of a whole sphere* Illumination-- is the deliberate application of light to achieve some aesthetic or practical effect
Table 1. SI photometry unitsvteQuantity Symbol[nb 1] SI unit Symbol Dimension Notes Luminous energy Qv [nb 2] lumen secondlm⋅s T⋅J [nb 3] units are sometimes called talbots Luminous flux Φv [nb 2] lumen (= cd⋅sr) lm J also called luminous power Luminous intensity Iv candela (= lm/sr) cd J an SI base unit, luminous flux per unit solid angle LuminanceLv candela per square metre cd/m2 L−2⋅J units are sometimes called nitsIlluminanceEv lux (= lm/m2) lxL−2⋅J used for light incident on a surface Luminous emittance Mv lux (= lm/m2) lx L−2⋅J used for light emitted from a surface Luminous exposure Hv lux secondlx⋅s L−2⋅T⋅J Luminous energy density ωv lumen second per metre3 lm⋅⋅m−3 L−3⋅T⋅J Luminous efficacy η [nb 2] lumen per wattlm/WM−1⋅L−2⋅T3⋅J ratio of luminous flux to radiant flux Luminous efficiency V 1 also called luminous coefficient
The 3 measurable quantities of light are: Luminous intensity-- which refers to the brightness of a light source Luminous flux-- is the rate at which light is emitted from a source and strikes the surface of a whole sphere Illumination-- is the deliberate application of light to achieve some aesthetic or practical effect