# What is light illuminance?

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## What is light luminance?

Simply put, luminance describes the amount of light that is emitted from, passed through, or reflected off an object. It is measured using candela per square meter, which is the concentration of luminous intensity per unit area in a specific path. Luminance is often confused with brightness.

## What is luminance and illuminance?

Illuminance is measured as the amount of light striking a surface. … Luminance, is what we measure off of the surface that has light hitting it. Luminance is the measurement of the product of the incident light and the surface – anything that is reflected.

## Is illuminance light intensity?

Illuminance is the metric that is used to measure the light intensity within a space. It is measured in footcandles or lux – it is the amount of light (lumens) falling on a surface (over any given square foot or square meter).

## What is the difference between illumination and illuminance?

As nouns the difference between illumination and illuminance

is that illumination is the act of illuminating, or supplying with light; the state of being illuminated while illuminance is (physics) the luminous flux incident on unit area of a surface; measured in lux or lumens.

## What is difference between illumination and luminous intensity?

Luminous intensity refers to the overall brightness, from a lamp LED, for example, without regard to the area of the light source. … The luminance is normally obtained by dividing the luminous intensity by the light source area.

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## What is meant by daylight factor?

Daylight Factor (DF) is defined as the ratio of the indoor daylight illuminance at a point within the enclosure to the outdoor illuminance at that point under the same unobstructed overcast sky.

## How do I find my illuminance?

The equation of the illuminance, E, of a small light source is E = P/ 4(pie)d^2, where P is the luminous flux (in lumens, lm) of the source and d is its distance from the surface. Suppose the luminous flux of a desk lamp is 1200 lm.

## What is the level of illuminance?

Indoor Light Levels

Activity Illuminance (lx, lumen/m2)
Performance of visual tasks of low contrast and very small size for prolonged periods of time 2000 – 5000
Performance of very prolonged and exacting visual tasks 5000 – 10000
Performance of very special visual tasks of extremely low contrast and small size 10000 – 20000