Register to reply

Force of attraction forumla

by esvion
Tags: attraction, force, forumla
Share this thread:
Nov24-08, 05:09 PM
P: 19
The force of attraction formula between two charges is


How does the inverse of r2 fit into the equation? I understand the concept of how distance would need to be the inverse in the function, but why is the distance (r) in the inverse squared? Is this the same principle of why s^-2 is the acceleration formula and time is square in the inverse?

Phys.Org News Partner Physics news on
Step lightly: All-optical transistor triggered by single photon promises advances in quantum applications
The unifying framework of symmetry reveals properties of a broad range of physical systems
What time is it in the universe?
Doc Al
Nov24-08, 06:01 PM
Doc Al's Avatar
P: 41,471
Coulomb's law is an example of an inverse square law, something quite common in physics. Read about it here: Inverse Square Law
Nov24-08, 07:06 PM
P: 19
I see! thanks!

Nov24-08, 09:33 PM
HW Helper
P: 7,131
Force of attraction forumla

Quote Quote by Doc Al View Post
Note that inverse square law is applies to point or spherical sources. For an infinitely (or very large) long line or cylinder, the ratio of force versus perpendicular distance to the line is 1/r. For an infinitely (or very large) plane, the force is constant (independent of distance).

Found the link for the other cases at the same site: electrical field

For the infinite line case, the field strenth is a function of charge "density" over the perpendicular distance "z" to the line ( ... / z).

For the infinite disc (plane) case, the limit as "R" approaches infinity, the [1 - z/sqrt(z^2 + R^2) ] term approaches [1 - 0], and the field strength is constant, independent of distance
Nov26-08, 03:11 AM
P: 6
Things get really cool when you start checking out far field proportionalities in systems of multipoles!

Register to reply

Related Discussions
Magnet's attraction/rejection Force Introductory Physics Homework 13
Attraction and gravitational force. Advanced Physics Homework 5
What Forumla? Introductory Physics Homework 6
Help... empirical forumla... : / Chemistry 1