Electrostatics and Inverse-Square Laws

Equations

coulaw.gif

From the Hyperphysics

Website

Wapplied = ∆ U = q∆V

V = Ed

Explanation of the derivation of the equations

Why forces that generate fields are governed by inverse-square laws

Imagine the source of the field is a spherical transmitter (like the button on a radio tower). A wave leaves it, and propagates out in 3-d space as an expanding sphere. Every bit of energy passing through the button is now diluted by being spread out across the surface area of that larger sphere, which is 4πr2. That’s why, in the full statement of Coulomb’s Law, 4πr2 appears in the denominator (Magnetic and Gravitational Fields show this effect, too!)

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