Date: Sun, 12 Dec 2010 22:24:57

Author: Urs Lauterburg

Subject: Re: Simple Rail Gun

Post:

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Paul,

If you make the whole arrangement smaller to fit within a B-field
produced by a horseshoe magnet you get much better results. In fact
that's our traditional arrangement to demonstrate the Lorentz force
on charges that move along a rolling rod on a rail. You can show the
effect of changing both of the polarities of the current as well as
of the B-field by flipping the magnet.

Regards form over here

Urs

Urs Lauterburg
Physics demonstrator
Physikalisches Institut
University of Bern
Switzerland

>Ok Dave,
>
>I just tried it.
>
>My little battery charger trips off after a few seconds. And it
>doesn't have enough power to get the roller started by itself.
>
>Here's the curious feature... The rod will continue rolling if
>given a small nudge. And it might even accelerate just a bit. It
>doesn't keep rolling if the power is off. But the thing about that
>is... it works it both directions. And it works in both directions
>regardless of the polarity of the power.
>
>Does this bother anyone else? Or can I choose to use either a
>left-hand rule or a right-hand rule depending on my mood?
>
>Paul
>
>
>On Nov 17, 2010, at 11:51 AM, david kardelis wrote:
>
>>Adam asked about my rail gun.
>>
>>Simple setup, 2 3/4" aluminum rods on the table about 1/2 meter
>>apart, Third aluminum rod laid on top. B field comes from the earth.
>>
>>The power supply is a emergency jumper battery , one lead hooked to
>>each rod on the table, see the thread on power supplies.
>>
>>Flip the switch and the rod rolls.
>>
>>I find I need to sand the aluminum rods before doing this as the
>>oxidation prevents good electrical contact. The rods do get pitted
>>along the contact points
>>
>>Here is a video on Photobucket I took quickly this morning
>>
>>
>>http://s366.photobucket.com/albums/oo108/dkardelis/Rail%20Gun/?action=viewĄt=003.mp4
>>
>>
>>
>>I tried using conduit this morning, to see if could get a longer
>>run, and a lighter "bullet". The conduit just welded itself
>>together when I flipped the switch,
>>
>>dave

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Paul,

If you make the whole arrangement smaller to fit within a B-field
produced by a horseshoe magnet you get much better results. In fact
that's our traditional arrangement to demonstrate the Lorentz force on
charges that move along a rolling rod on a rail. You can show the
effect of changing both of the polarities of the current as well as of
the B-field by flipping the magnet.

Regards form over here

Urs

Urs Lauterburg
Physics demonstrator
Physikalisches Institut
University of Bern
Switzerland

Ok Dave,

I just tried it.

My little battery charger trips off after
a few seconds. And it doesn't have enough power to get the
roller started by itself.

Here's the curious feature... The
rod will continue rolling if given a small nudge. And it might
even accelerate just a bit. It doesn't keep rolling if the power
is off. But the thing about that is... it works it both
directions. And it works in both directions regardless of the
polarity of the power.

Does this bother anyone else? Or
can I choose to use either a left-hand rule or a right-hand rule
depending on my mood?

Paul


On Nov 17, 2010, at 11:51 AM, david
kardelis wrote:

Adam asked about my rail gun.

Simple setup, 2 3/4" aluminum rods on the table about 1/2 meter
apart, Third aluminum rod laid on top. B field comes from the
earth.

The power supply is a emergency jumper battery , one lead hooked to
each rod on the table, see the thread on power supplies.

Flip the switch and the rod rolls.

I find I need to sand the aluminum rods before doing this as the
oxidation prevents good electrical contact. The rods do get pitted
along the contact points

Here is a video on Photobucket I took quickly this morning


http://s366.photobucket.com/albums/oo108/dkardelis/Rail%20Gun/?action=view¤t=003.mp4



I tried using conduit this morning, to see if could get a
longer run, and a lighter "bullet". The conduit
just welded itself together when I flipped the switch,

dave




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