1. What is Luminous Flux?

Luminous flux (measured in lumens) is a measure of the total quantity of visible light emitted by a source. It accounts for the sensitivity of the human eye to different wavelengths of light.

2. How Does the Calculator Work?

The calculator uses the lumen calculation formula:

Where:

• Light Intensity — Measured in candela (cd), the base unit of luminous intensity
• Conversion Factor — Typically 12.57 (4π) for isotropic light sources

Explanation: The formula converts luminous intensity (measured in candela) to luminous flux (measured in lumens) by accounting for the angular distribution of light.

3. Importance of Lumen Calculation

Details: Knowing the luminous flux is essential for lighting design, energy efficiency calculations, and comparing different light sources.

4. Using the Calculator

Tips: Enter the light intensity in candela and the appropriate conversion factor (12.57 for isotropic sources). All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between lumens and candela?
A: Candela measures luminous intensity (light in a specific direction), while lumens measure total visible light output in all directions.

Q2: When should I use a different conversion factor?
A: Use different factors for non-isotropic light sources where the light distribution isn't uniform in all directions.

Q3: How many lumens is a 100W incandescent bulb?
A: Approximately 1600 lumens, though this varies by bulb design and age.

Q4: Why is the conversion factor 12.57?
A: It's 4π steradians, representing the total solid angle around a sphere (isotropic source).

Q5: Can I use this for LED lighting?
A: Yes, but be aware that LED light distribution may not be perfectly isotropic.