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# Re: Lorentz force

- To: femm@yahoogroups.com
- Subject: Re: Lorentz force
- From: "lorikloesel" <lkloesel@mail.qnet.com>
- Date: Thu, 23 May 2002 13:41:44 -0000
- In-reply-to: <3C0BE5E4.E6453672@foster-miller.com>
- User-agent: eGroups-EW/0.82

    I'm assuming that this shows up as a 120Hz vibration in a 60Hz
    driven system? The amplitude of the mechanical vibration is related to
    the mass of the object and the strength of the 2x force?

    Thanks

    --- In femm@y..., David Meeker <dmeeker@f...> wrote:
    > mercedes sampere wrote:
    >
    > > Hi femm users!
    > > Could anybody tell me what does "2x frecuency force mean" when I
    ask for
    > > Lorentz force?
    > > Ex:
    > > Steady-state force:
    > > x-component: -3.027513e-002 N/m
    > > y-component: -1.022735e-004 N/m
    > > 2x Frequency force:
    > > x-component: -3.011e-002 - j 9.877e-003 N/m
    > > y-component: -1.059e-004 - j 5.189e-005 N/m
    > >
    > > Thank you very much
    > > Mercedes.
    > >
    >
    > Well, force equals the integral of J X B. If you are evaluating a
    > time-harmonic problem, current density J varies sinusoidally in
    time, and the
    > resulting flux density B also varies sinusoidally in time, with both
    J and B
    > oscillating at the same frequency. If you multiply together two
    sine waves,
    > you get one portion that is constant with respect to time, and one
    portion
    > that varies at twice the base frequency, e.g.:
    >
    > Sin[t]^2 = (1 - Cos[2*t])/2
    >
    > Therefore, since the force is the product of sinusoidally varying
    quantities,
    > you get a constant component and a 2x component, and what femm is
    reporting
    > is the net constant and 2x components. Part of the purpose of
    making 3 phase
    > systems is so that the 2x components all cancel out, leaving only
    the part of
    > force that is constant with respect to time.
    >
    > Dave.

- Follow-Ups:
  - contactor force
    - From: "lanzador" <lanzador@ozu.es>
  - Re: [femm] Re: Lorentz force
    - From: David Meeker <dmeeker@ieee.org>

- References:
  - Re: [femm] Lorentz force
    - From: David Meeker <dmeeker@foster-miller.com>

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