Re: Particle Visualization



Monitek wrote:
> "PD" <TheDraperFamily@xxxxxxxxx> wrote in message
> news:1117910109.935761.160440@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> >
> >
> > Monitek wrote:
> >> "PD" <TheDraperFamily@xxxxxxxxx> wrote in message
> >> news:1117836516.263186.193360@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> >> >
> >> >
> >> > Monitek wrote:
> >> >> "PD" <TheDraperFamily@xxxxxxxxx> wrote in message
> >> >> news:1117761290.393006.173510@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> >> >> >
> >> >> >
> >> >> > Monitek wrote:
> >> >> >> "PD" <TheDraperFamily@xxxxxxxxx> wrote in message
> >> >> >> news:1117754586.654490.24160@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> >> >> >> >
> >> >> >> snip
> >> >> >> >
> >> >> >> > That is flat wrong. A changing magnetic field in the evacuated
> >> >> >> > (or
> >> >> >> > air-filled) gap of a dipole magnet will produce a measurable
> >> >> >> > electric
> >> >> >> > field in that gap, which can be tested by the placement of a
> >> >> >> > *stationary* electron or other charged, nonconductive object in
> >> >> >> > that
> >> >> >> > gap.
> >> >> >> >
> >> >> >>
> >> >> >> There is something a bit iffy about the above. First of all an
> >> >> >> electon
> >> >> >> can
> >> >> >> be moved by a magnetic field
> >> >> >
> >> >> > A *stationary* electron is moved by a magnetic field? Are you sure?
> >> >> >
> >> >>
> >> >> As electrons are never *stationary* that is a hypothetical bu so what.
> >> >> A
> >> >> changing magnetic field. Those were your starting conditions.
> >> >
> >> > Point taken, but the acceleration caused by the induced electric field
> >> > will be in a specific direction and a specific magnitude. The magnetic
> >> > field's effect on an electron's purely stochastic motion would not have
> >> > that behavior.
> >> >
> >>
> >> Yes the effect is directional and it would be superimposed on the random
> >> motion. Do we have a chicken and egg situation here. If you are right
> >> then
> >> stationary electrons say can never react to a magnetic field and it is
> >> only
> >> the magnetic fields which react not the electric field, then
> >> electromagnetic
> >> induction would never get started unless the receiving charges were
> >> moving.
> >
>
> > But this is counter to experiment. The direction of the magnetic force
> > acting on a moving charge is different than the direction the force due
> > to the induced electric field. Moreover, see the purely static case in
> > another reply - *no* motion of charges in the gap, yet the presence of
> > the field detected.
> >
>
> The field in the gap of your electro magnet is due to the charges in the
> magnet material moving to create a potential difference at the poles when
> the emf of the electromagnet is turned off.

OK, let's sketch it. The dipole tips are vertically aligned, so that
the B-field is vertical. Now decrease the B-field by any of the chosen
methods. The induced E-field, as probed by the force on a test charge
placed in the gap, will be *horizontal* and tangent to a circle
centered around the axis through the center of the pole tips. In fact,
if you drew electric field lines, you would see they form a complete,
closed, horizontal loop in the gap. Note how different this is from an
electrostatic field generated by electric charge, where the field lines
*always* originate at a positive charge (or come from infinity) and
*always* end at a negative charge (or come from infinity). Now, suppose
you tell me how you can distribute charge in the pole tips to generate
electric field lines that form closed loops that never touch the pole
tips.

>
> >> So as EMR moves electrons in the background so to speak
> >
> > I'm not sure how this pertains to the case at hand...
> >
> >> then we have a
> >> situation such that the first every EMR wave could not get started. There
> >> must have been a first ever in the history of the universe EMR wave.
> >>
> >> >>
> >> >> >> which does not indicate any electric field
> >> >> >> being present. Personally I would have put a capacitor in the gap
> >> >> >> if I
> >> >> >> wanted to measure electric field strength.
> >> >> >
> >> >> > Yes, that would work too, with a voltmeter strapped across it.
> >> >> >
> >> >> >> Secondly how do you get your
> >> >> >> magnetic dipole magnet to change its magnetic field?
> >> >> >>
> >> >> >
> >> >> > Lots of ways, any of which would work
> >> >> > 1. Change the current in the electromagnet
> >> >>
> >> >> oops charged particles are involved again.
> >> >>
> >> >> > 2. Increase or decrease the space between the pole tips
> >> >>
> >> >> moving charged particles again.
> >> >
> >> > Really? What charged particles are relevant here? Note the coils do not
> >> > have to move. Nor does it have to be an electromagnet for that matter.
> >> >
> >>
> >> The ones which loop to create the poles in the first place!
> >
> > Are you talking about the electrons in the magnetic domains of the
> > iron?
> >
>
> Yes if it is not an electro magnet and otherwise the moving charge in your
> quenched electro-magnet material.

Fine. See my paragraph above talking about the shape of the induced E
field, and tell me how the redistributed domains do that.

>
> Why do you call it quenched? That usually means immersing in water or some
> other fluid.

It's superconducting magnet jargon. Never mind.

>
> >>
> >> >>
> >> >> > 3. Move the magnet to one side, so that the electron now is sitting
> >> >> > in
> >> >> > a region of weaker field
> >> >>
> >> >>
> >> >> > 4. Insert a piece of iron in half the gap (where the electron
> >> >> > isn't),
> >> >> > creating a magnetic parallel circuit with a shunt in one leg
> >> >>
> >> >> > 5. Heat the magnet if it's a permanent magnet
> >> >> > I'd like to see how you can assert these are all examples of
> >> >> > induction.
> >> >> >
> >> >> You have forgotten hitting the magnet with a hammer to disturb the
> >> >> domain
> >> >> alignment.
> >> >>
> >> >> A changing magnetic field induced a current in a conductor- that is
> >> >> induction.
> >> >>
> >> >> > But don't take my word for it. Do the experiment yourself, as
> >> >> > Faraday
> >> >> > would.
> >> >> > I've seen the effect myself, in the form of a corona discharge in
> >> >> > the
> >> >> > gap of a superconducting dipole that's just quenched. Quite
> >> >> > frightening. And quite convincing.
> >> >> >
> >> >>
> >> >> In this case the magnet itself is acting as an open loop inductor (it
> >> >> being
> >> >> a conductor) and the collapsing magnetic field will create any
> >> >> potential
> >> >
> >> > Potential! Yes! What kind of potential??
> >>
> >> The electric potential is created by electromagnetic induction. In the
> >> same
> >> way that the alternating potential is created during the propagation of
> >> EMR.
> >> The potential is caused by the magnetic field but is not part of the
> >> intrinsic properties of the field its self.
> >
> > Excuse me. Where there is a gradient to the electric potential, there
> > is an electric field by definition. You are right, the electric
> > potential is not part of the *magnetic* field, but what you've just
> > said, and what is the truth, is that the change in the magnetic field
> > causes an electric field (or equivalently, an electric potential
> > gradient). Saying that it is not an electric field but an electric
> > potential is a denial of definitions.
> >
>
> There is a field between the zones of different potential and, of course
> charged, particles had to move to create the potential difference.
> They were moved by the collapsing magnetic field in your electromagnet.
>
> >>
> >> >
> >> >> required to create a current flow. I have seen similar effects when
> >> >> you
> >> >> "charge" and inductor with dc current and then remove the current
> >> >> source
> >> >> from the inductor you get spectacular sparks.
> >> >>
> >> >> > PD
> >> >> >
> >> >>
> >> >> So, if I rotate a bar magnet next to a flat plate capacitor such that
> >> >> the
> >> >> magnetic field in the region of the capacitor will alternate, I will
> >> >> measure
> >> >> an alternating charge displacement in the circuit of the capacitor?
> >> >>
> >> >> I dont think so.
> >> >>
> >> >
> >> > Try it!
> >> >
> >>
> >> OK you have persuaded me to waste my time. You will have will have to
> >> wait
> >> till Monday.
> >
> > Wonderful! At least you're approaching it like a physicist.
> >
> >> Basically will a rotating magnet past two small 1 cm square
> >> copper plates separated with 0.002" mica *** and look for some AC on
> >> the
> >> scope. The connecting wires will be twisted pair to avoid pick up from
> >> the
> >> field.
> >
> > You will still have a systematic error due to pickup in the twisted
> > pair. The best way to address this is to repeat the measurement with
> > several thicknesses of mica and plot the results. The measured signal
> > is expected to be linear in the thickness (why?), with the intercept
> > representing the background to the true signal in the capacitor gap.
> >
>
> The value of a capacitor is inversely proportional to the distance between
> its plates.
> So if I use coaxial cable which is purely capacitive that will stop the pick
> up from the magnetic field.
> Would it not be better to use 2 different values of capacitance and subtract
> the results thereby eliminating pick-up in the apparatus completely.
> repeating the experiment with different pairs of capactor values?

Subtracting the two is equivalent to the fit-and-intercept method I
suggested. It might still be better to take more than two data points,
if only to assure yourself that the dependence is linear as expected.
With only two data points, you can only assume that it is linear.

>
>
> >>
> >> What order of magnitude do you think I should be looking for?
> >
> > This is something you can calculate.
> > 1) Measure the magnetic field of the bar magnet. This you can do with a
> > calibration. Put a square loop of wire with one leg of loop in the
> > field of the magnet, and the opposite side anchored down. Run a known
> > current through the wire and measure the force on the wire. If you're
> > clever, you'll arrange the force to be vertically up, so that you can
> > counterbalance the force with small weights (plastic paper clips) and
> > tweaking the current until you get equilibrium; the weight down equals
> > the magnetic force up, and the latter is F = I*B*L.
> > 2) The rate of change of the magnetic field in the gap will be
> > proportional to 2*B*f, where f is the rotation frequency of the magnet.
> > 3) Maxwell's equations will then tell you the magnitude of the induced
> > E field.
> > 4) From the capacitor geometry, you can predict the magnitude of the
> > induced voltage, basically V = E*d.
> >
>
> You have forgotten to calculate where the E field will show up.
> We will do the calculations if we detect anything.

My step (3) tells you where the E-field will show up. As far as doing
the calculations afterwards... Gee, it's always been my experience as
an experimentalist that it's better to do the calculations beforehand,
so that you know roughly what size of effect you're trying to see, so
that you have a chance to tweak the experimental design in case your
experimental sensitivity is too low or plagued by background.

>
> >>
> >> Basically if I measure a magnetic field then I will find charged
> >> particles
> >> which have created it in close proximity.
> >>
> >
> > That's what we're checking, aren't we?
> >
> > Consider the sun and the earth. Calculate the magnetic field required
> > to generate a power delivery from the sun to the Earth's surface of 1
> > kW/m^2. (That is, what's the strength of the magnetic field at the
> > Earth's surface?)
> > The source charged particles of this magnetic field MUST be at the sun,
> > correct? Calculate the current required at the surface of the sun to
> > induce a magnetic field of that size at the Earth. That's your model.
> > Does it look reasonable to you?
> >
> > PD
> >
>
> That doesnt sound like anything I have said it doesnt sound reasonable
> either. As an aside I dont think a magnetic field can travel that far and be
> measurable. The induction cycle occurs at sub millimetre distances given the
> circumstances which you quote above. I am saying that EMR which alternates
> from magnetic to electric energy requires charged particles in the locality
> of where it is to create a magnetic field. I am saying that to propagate by
> electromagnetc induction EMR must rely on the vacuum being a conductor so
> that the magnetic cycle can induce a current in the vacuum.
>

OK, let me put it to you this way. Electromagnetic energy is
*definitely* delivered to the surface of the earth at a rate of 1
kW/m^2. That energy must be carried via an electromagnetic process,
through 93,000,000 miles of vacuum to the Earth. How you YOU say it
gets here?

PD

.