# inverse-square law

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## in·verse-square law

(ĭn′vûrs-skwâr′)
n.
The principle in physics that the effect of certain forces, such as light, sound, and gravity, on an object varies by the inverse square of the distance between the object and the source of the force. For example, an object placed three feet away from a light source will receive only one ninth ( 1/32 , the inverse of 3 squared) as much illumination as an object placed one foot from the light.

## inverse-square law

A principle in physics dealing with forces that spread equally in all directions (such as sound, light, and gravity) and describing how the strength of these forces weakens over increasing distance. According to this principle, the effect of the force on an object changes by the inverse square of the distance between the object and the force's source. For example, an object placed three feet away from a light source will receive only one-ninth (1/32, the inverse of 3 squared) as much illumination as an object placed one foot from the light.
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Both light and heat follow the inverse-square law, which means they decrease at a rate proportional to the square of the distance from their source.
In physics, the intensity of light is inversely proportional to the square of the distance from a light source as shown in (1), which is called the inverse-square law. The light from a point source can be put in the following form:
This law was called Lotka's inverse-square law. The value obtained in this article for constant C was approximately 6/I2.
Early on, Isaac Newton (1642-1727) developed his laws of motion and inferred the inverse-square law of gravitational attraction.
Change of SL with distance from the source is explained by the inverse-square law. Since sound intensity measures the distribution of sound power over a surface, one watt (W) of sound power distributed over a small area has a greater intensity than 1 W distributed over a large area.
All electromagnetic waves obey the inverse-square law in free space.
Consequently, the practicable version for Rindler's Lorentz force law becomes the same as a time-retarded version for Newton's well-known inverse-square law
In 1750, John Michel theorized that permanent magnet has north and south poles that attract or repel each other according to an inverse-square law that is similar to Coulomb's law of force.
When using flash outdoors for any of the techniques described here, it pays to remember the inverse-square law. This stipulates that as you double the subject distance from the flash, the amount of light reaching the subject reduces by a quarter.
For example, the observed behavior of the Earth revolving around the sun can be perfectly explained if the sun has a net positive charge and the planets have a net negative charge, since opposite charges attract and the force is an inverse-square law, exactly like the increasingly discredited theory of gravity.

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