Calculate how intensity (light, sound, gravity) changes with distance from a source.
Parameters
Calculation Results
Enter initial values and the new parameter to calculate
About this calculator
Quick Reference
IIntensity (Light, Gravity, etc.)
rDistance from Source
SourceMust be a point source
Overview
The inverse-square law states that a specified physical quantity (like light intensity or gravitational force) is inversely proportional to the square of the distance from the source of that physical quantity.
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Pro Tips
If you double the distance, the intensity becomes $1/4$ (25%) of the original.
If you triple the distance, the intensity becomes $1/9$ (~11%) of the original.
This law applies to point sources radiating uniformly in all directions.
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Fun Facts
"The law applies to gravity, electric fields, light, sound, and even radiation."
"Professional photographers use this law to calculate how much light will reach their subject at different distances."
"The sun's light intensity on Pluto is about 1600 times less than on Earth because it is about 40 times further away."
