Enter your Initial Intensity (I₁), Initial Distance (d₁), and Final Distance (d₂) to calculate the Final Intensity (I₂) using the Inverse Square Law Calculator. Choose your Dose Rate and Distance Units, and you'll also get the Intensity Ratio, Distance Ratio, and Reduction Factor.
Final Intensity (I₂)
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Intensity Ratio (I₂/I₁)
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Distance Ratio (d₂/d₁)
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Reduction Factor
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The inverse square law states that the intensity of radiation from a point source decreases with the square of the distance from the source. As you double the distance, the radiation intensity becomes one-fourth of the original value.
Use the formula I₂ = I₁ × (d₁/d₂)², where I₁ is initial intensity, I₂ is final intensity, d₁ is initial distance, and d₂ is final distance. Enter your values into the calculator for automatic computation.
When distance increases from 1 to 3 meters, the intensity reduces by a factor of 9 (3²). This means the radiation intensity at 3 meters is only 1/9th or about 11% of the intensity at 1 meter.
Common examples include gamma radiation, X-rays, light intensity, sound intensity, and gravitational force. Any energy that radiates uniformly from a point source follows this law.
It helps radiation workers calculate safe distances from radiation sources. Understanding this law allows for proper shielding design and dose reduction strategies in medical, industrial, and nuclear applications.
The law applies to gamma rays, X-rays, and other electromagnetic radiation. However, it may not apply to beta particles or neutrons in certain conditions due to scattering and absorption effects.
The law is most accurate for point sources in a vacuum or air with minimal scattering. In practice, factors like air absorption, scattering, and source geometry may cause slight deviations from theoretical values.
Common units include roentgen per hour (R/hr), milliroentgen per hour (mR/hr), sievert per hour (Sv/hr), and millisievert per hour (mSv/hr). The calculator supports multiple unit conversions for convenience.