Free Light Intensity Calculator
Calculate light intensity variation with distance using the inverse square law: I = P / (4 * pi * r²).
W
m
Intensity
1.9894 W/m²
Intensity vs Light Source Power
Light Intensity (Inverse Square Law)
Light intensity from a point source decreases with the square of the distance.
Formula
I = P / (4 * pi * r²)
where P is the total power output and r is the distance from the source. Doubling the distance reduces intensity by a factor of four.
Example Calculation
A 100 W light bulb at 2 meters distance.
- 01I = P / (4*pi*r²)
- 02I = 100 / (4*pi*4)
- 03I = 100 / 50.27
- 04I = 1.989 W/m²
Frequently Asked Questions
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