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Re: Magnets repel more weakly than attract

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On Friday, June 24, 2016 at 7:30:06 AM UTC+10, benj wrote:
> On 6/22/2016 10:07 PM, Sylvia Else wrote:
> >
> > Now consider two magnets. When orientated so that they attract, the
> > field of each causes further alignment of the domains in the other, and
> > that alignment reinforces the field, increasing the attraction.
> >
> > Now orientate the magnets so that they repel. The field of each reduces
> > the field that's orientating the domains in the other. Some of those
> > domains lose orientation, reducing the total field. Net result - a lower
> > repulsive force than there was previously an attractive force.
> >
> > So there's nothing to see here. Move along.
> 
> Great theory "Sylvia" but you don't have much to back it up. You know 
> they are called permanent magnets because the domains DO NOT "lose 
> orientation" unlike iron. I'm sure one might propose a slight spring 
> like deflection of domains which snap back once field is gone, but I 
> doubt this effect is significant. In fact, I doubt there are very few 
> credible measurements of ANY of this including the alleged difference 
> between attraction and repulsion.

It's easy enough to find measurements online:
https://www.supermagnete.de/eng/faq/Is-the-attraction-between-magnets-as-high-as-the-repulsion

You could also do it the old-fashioned way: measure it yourself. Measurement trumps speculation.

The electrostatic version can be fun, too. Since everybody knows that a positively charged body will repel a positively charged body, a demonstration showing attraction instead has some impact. (It isn't quite the same as the magnet version - in the electrostatic version, it's the induced dipole competing with the monopole, rather than the induced dipole reinforcing or reducing the permanent dipole.)

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Magnets repel more weakly than attract omnilobe@gmail.com - 2016-06-21 16:08 -0700
  Magnets repel more weakly than attract john <johnsefton288@gmail.com> - 2016-06-21 16:20 -0700
  Re: Magnets repel more weakly than attract "reber g=emc^2" <herbertglazier0@gmail.com> - 2016-06-21 19:31 -0700
    Re: Magnets repel more weakly than attract omnilobe@gmail.com - 2016-06-21 21:02 -0700
  Re: Magnets repel more weakly than attract Sylvia Else <sylvia@not.at.this.address> - 2016-06-22 15:57 +1000
    Re: Magnets repel more weakly than attract omnilobe@gmail.com - 2016-06-22 08:28 -0700
      Re: Magnets repel more weakly than attract Sylvia Else <sylvia@not.at.this.address> - 2016-06-23 12:07 +1000
        Re: Magnets repel more weakly than attract benj <benj@nobody.net> - 2016-06-23 17:29 -0400
          Re: Magnets repel more weakly than attract Sylvia Else <sylvia@not.at.this.address> - 2016-06-24 10:10 +1000
            Re: Magnets repel more weakly than attract "reber g=emc^2" <herbertglazier0@gmail.com> - 2016-06-24 08:44 -0700
          Re: Magnets repel more weakly than attract Timo <timo@physics.uq.edu.au> - 2016-06-24 15:05 -0700
          Re: Magnets repel more weakly than attract Timo <timo@physics.uq.edu.au> - 2016-06-24 03:36 -0700
          Re: Magnets repel more weakly than attract "reber g=emc^2" <herbertglazier0@gmail.com> - 2016-06-23 16:42 -0700
          Re: Magnets repel more weakly than attract Timo <timo@physics.uq.edu.au> - 2016-06-24 17:56 -0700
        Re: Magnets repel more weakly than attract "reber g=emc^2" <herbertglazier0@gmail.com> - 2016-06-23 15:32 -0700
      Re: Magnets repel more weakly than attract Helmut Wabnig <hwabnig@.- --- -.dotat> - 2016-06-23 07:20 +0200
    Re: Magnets repel more weakly than attract "reber g=emc^2" <herbertglazier0@gmail.com> - 2016-06-22 11:47 -0700
      Re: Magnets repel more weakly than attract benj <benj@nobody.net> - 2016-06-22 16:17 -0400
        Re: Magnets repel more weakly than attract "reber g=emc^2" <herbertglazier0@gmail.com> - 2016-06-22 15:45 -0700
  Re: Magnets repel more weakly than attract "Y.Porat" <y.y.porat@gmail.com> - 2016-06-23 02:32 -0700
  Re: Magnets repel more weakly than attract "reber g=emc^2" <herbertglazier0@gmail.com> - 2016-06-24 08:41 -0700
  Re: Magnets repel more weakly than attract "reber g=emc^2" <herbertglazier0@gmail.com> - 2016-06-23 15:30 -0700
  Re: Magnets repel more weakly than attract "reber g=emc^2" <herbertglazier0@gmail.com> - 2016-06-23 16:41 -0700

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