Calculating Light Level at a Point

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SUMMARY

The discussion centers on calculating light levels in footcandles for urban planning purposes. The formula used is footcandles = lumens of the light source / (distance from the light source in feet)^2. Eric confirms that the distance should be measured in feet, aligning with the definition of a footcandle as lumens per square foot. This clarification ensures accurate calculations for lighting regulations in urban planning.

PREREQUISITES
  • Understanding of basic physics concepts related to light and illumination
  • Familiarity with the unit of measurement for light levels, specifically footcandles
  • Knowledge of the formula for calculating light levels from lumens
  • Basic skills in urban planning and lighting regulations
NEXT STEPS
  • Research the principles of photometry and how light levels are measured
  • Explore the impact of distance on light intensity and distribution
  • Learn about different lighting sources and their lumen output
  • Investigate urban lighting regulations and standards for footcandle requirements
USEFUL FOR

Urban planners, lighting designers, architects, and anyone involved in compliance with lighting regulations and calculations of illumination levels.

cmdrico7812
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I haven't used my high school physics education in a really long time but I need to here at work for a very simple problem. I am an urban planner and we deal with lighting regulations a lot. I am trying to calculate the light level (in footcandles) at a given point. I am using the following general equation:

[footcandles] = [light level in lumens of the source light] / [direct distance from point to light source]^2

All I need to know is what units do I use to measure the distance? Meters, feet, inches? Would I measure the distance in feet since my light unit is footcandles? I know the standard scientific measurement unit is meters or some derivation there of, but I wanted to ask here just to be sure. Many thanks in advance.

Eric
 
Last edited:
Science news on Phys.org
Feet. A footcandle is defined in units of lumens/ft^2.
 

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