Re: On 1/4*Pi in Coulomb's law

[Doug Craigen <dcc@ESCAPE.CA>]

Robert A Cohen wrote:
> It seems the only reason why students might be confused by the 4*pi in
> Coulomb's law is because there is no 4*pi in the gravitational law.
> Perhaps we should introduce the 4*pi in the gravitational law.  Would it
> be any less abstract for students to have gravity inversely proportional
> to surface area?

The difference is that we scarcely talk about "gravitational field". I
actually do talk about these.  I set up an analogy where
Fe = q*E       Fg = m*g
We = q*E*d     Wg = m*g*h
from a point source:  E = constant*q_source./area_of_surface
             general"g" = constant*m_source./area_of_surface

I've wondered if I'm the only person to do this though.  Certainly the
idea of a gravitational field is not talked about enough in the intro
books I've seen for a 4pi in the gravitational law to make any sense.

\_/^\_/^\_/^\_/^\_/^\_/^\_/^\_/^\_/^\_/^\_/^\_/^\_/^\

Doug Craigen
          http://www.dctech.com/physics/about_dc.html