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Inverse Square Law for Point Source:
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The Inverse Square Law describes how the intensity of light (or other radiation) from a point source decreases with the square of the distance from the source. This fundamental principle applies to all point sources that radiate uniformly in all directions.
The calculator uses the inverse square law formula:
Where:
Explanation: The formula shows that light intensity is inversely proportional to the square of the distance from the source. Doubling the distance reduces intensity to one-quarter of its original value.
Details: Accurate light intensity calculation is crucial for lighting design, photography, radiation safety, architectural planning, and understanding energy distribution from various light sources.
Tips: Enter power in watts (W) and distance in meters (m). Both values must be positive numbers. The calculator will compute the light intensity in watts per square meter (W/m²).
Q1: Why does light intensity follow an inverse square relationship?
A: Because light spreads out uniformly in all directions from a point source, covering a surface area that increases with the square of the distance.
Q2: What are typical light intensity values?
A: Direct sunlight is about 1000 W/m², office lighting is around 300-500 lux, and moonlight is approximately 0.1 lux.
Q3: Does this law apply to all light sources?
A: It applies to point sources that radiate uniformly. For directional sources like lasers or focused beams, the relationship may differ.
Q4: How does this relate to illuminance in lux?
A: Lux measures illuminance (perceived brightness by human eye), while W/m² measures irradiance (energy per unit area). Conversion depends on the light spectrum.
Q5: What are practical applications of this calculation?
A: Lighting design for buildings and streets, photography exposure settings, radiation safety calculations, and solar panel placement optimization.