Inverse square law
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inverse square law physics definition examples
The inverse square law states that the intensity of an effect from a point source is inversely proportional to the square of the distance from it:
[
I \propto \frac{1}{r^2}
]
or, comparing two distances:
[
\frac{I_1}{I_2}=\frac{r_2^2}{r_1^2}
]
Where:
- (I) = intensity, such as light, radiation, or sound energy per unit area
- (r) = distance from the source
Meaning:
- Double the distance, intensity becomes (1/4).
- Triple the distance, intensity becomes (1/9).
- Halve the distance, intensity becomes (4) times greater.
It occurs because the same emitted energy spreads over the surface of an expanding sphere, whose area is (4\pi r^2). It applies approximately to light and radiation from a small point source, gravity, and electrostatic force. This overview explains the geometric basis.
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