1. What is the Light Intensity Formula?

Definition: This calculator determines the luminous intensity at a given distance from a point light source using the inverse square law.

Purpose: It helps lighting designers, photographers, and engineers calculate how light intensity diminishes with distance from the source.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( I \) — Light intensity (candela)
• \( P \) — Radiant power (watts)
• \( d \) — Distance from source (meters)
• \( \pi \) — Pi (approximately 3.14159)

Explanation: The formula shows that light intensity follows an inverse square law - it decreases with the square of the distance from the source.

3. Importance of Light Intensity Calculation

Details: Proper light intensity calculation ensures adequate illumination for tasks, energy efficiency, and visual comfort in lighting design.

4. Using the Calculator

Tips: Enter the light source power in watts and the distance from the source in meters. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Why does light intensity decrease with distance?
A: Because light spreads out over a larger area (sphere surface) as distance increases, following the inverse square law.

Q2: What's a typical light bulb power?
A: LED bulbs range from 4-20 watts, CFLs 5-30 watts, and incandescent 40-150 watts, but check your specific bulb.

Q3: Does this work for all light sources?
A: It works best for point sources. For extended sources or directional lights, additional factors must be considered.

Q4: How does this relate to lux or lumens?
A: 1 lux = 1 lumen/m². Candela measures luminous intensity while lumens measure total light output.

Q5: What if my light isn't radiating equally in all directions?
A: You would need to account for the beam angle and use a different formula that includes the radiation pattern.