How Do You Calculate Luminous Flux from Radiant Flux?

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In summary, the luminous flux of the source with a radiant flux of 3 watts and a relative luminosity of 0.685 at 6000 Angstrom is 1403.565 lumens.
  • #1
Amith2006
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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
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


Yes, your solution is correct. You have correctly applied the formula for calculating total luminous flux, taking into account the given values for radiant flux and relative luminosity. The peak value of luminous efficacy in a photopic vision curve is 683 lumens/watt, which you have also used correctly in your calculation. Therefore, the luminous flux of the source is 1403.565 lumens.
 

1. What is the photopic efficacy problem?

The photopic efficacy problem is a phenomenon in which the human eye's sensitivity to light is highest during the daytime, specifically in the range of 555-570 nanometers, but decreases at lower light levels. This means that the eye's ability to detect and perceive light diminishes as the light intensity decreases.

2. How does the photopic efficacy problem affect our perception of light?

The photopic efficacy problem can affect our perception of light by making it difficult to accurately perceive low light levels. This can lead to visual illusions, difficulty seeing in dimly lit environments, and reduced color perception. It can also impact our ability to detect objects or hazards in low light conditions.

3. What causes the photopic efficacy problem?

The photopic efficacy problem is caused by the structure and function of the human eye. Our eyes contain two types of photoreceptor cells: rods and cones. Cones are responsible for color vision and are most sensitive to light in the daytime, while rods are responsible for low light vision and are more sensitive in dim lighting. As light levels decrease, the cones become less active, leading to decreased sensitivity to light.

4. How is the photopic efficacy problem measured?

The photopic efficacy problem can be measured using a variety of methods, including psychophysical experiments and electrophysiological recordings. Psychophysical experiments involve measuring a person's ability to detect and discriminate different levels of light, while electrophysiological recordings involve measuring the electrical activity of the eye in response to light stimuli.

5. Can the photopic efficacy problem be solved?

While the photopic efficacy problem cannot be completely solved, there are ways to mitigate its effects. This includes using artificial lighting that mimics natural daylight, using adaptive optics to compensate for individual differences in eye structure, and using contrast enhancement techniques to improve visual perception in low light conditions.

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