Calculation of Luminous flux

In summary, the question is asking for the luminous flux of a source given the radiant flux, relative luminosity at 6000 Angstrom, and the peak value of luminous efficacy in a photopic vision curve. After solving for the total luminous flux using the given values and correcting the peak value of luminous efficacy, the resulting luminous flux is approximately 1403.565 lumens.
  • #1
Amith2006
427
2
Please help me with this problem.
# A screen receives 3 watts of radiant flux of wavelength 6000 Angstrom. One lumen is equivalent to 1.5 x 10^(-3) watts of monochromatic light of wavelength 5550 Angstrom. If the relative luminosity for 6000 Angstrom is 0.685 while that for 5550 Angstrom is 1, then what is the luminous flux of the source?
I solved it in the following way:
Here radiant flux = 3 watts, Relative luminosity at 6000 Angstrom = 0.685, Peak value of luminous efficacy in a photopic vision curve = 683 lumen/watt
Total luminous flux = (radiant flux) x (Relative luminosity) x (Peak value of luminous efficacy in a photopic vision curve)
= 3 x 0.685 x 683
= 1403.565 lumens
Is it right?
 
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  • #2
Since you are given
Amith2006 said:
One lumen is equivalent to 1.5 x 10^(-3) watts of monochromatic light of wavelength 5550 Angstrom
perhaps you are meant to use 1/(1.5 x 10^(-3)) =667 lumen/W, not 683.
 

1. How is luminous flux measured?

Luminous flux is measured in units of lumens (lm), which is a measure of the total amount of visible light emitted by a source per unit time.

2. What is the formula for calculating luminous flux?

Luminous flux can be calculated using the formula: luminous flux (lm) = luminous efficacy (lm/W) x power input (W). This takes into account the efficiency of the light source in converting electrical energy into visible light.

3. How does color temperature affect luminous flux?

Color temperature, which is a measure of the color appearance of light, does not directly affect luminous flux. However, the human eye is more sensitive to certain colors of light, which can impact the perceived brightness of a light source.

4. What factors can affect the accuracy of luminous flux calculations?

Several factors can affect the accuracy of luminous flux calculations, including the quality and condition of the light source, the measurement equipment used, and any external factors that may influence the measurement, such as ambient lighting.

5. How is luminous flux used in lighting design?

Luminous flux is an important factor in lighting design as it helps determine the amount of light needed for a specific space or task. It is also used to compare the brightness of different light sources and to ensure that lighting meets certain standards and regulations.

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