Date: Sun, 12 Dec 2010 20:12:17

Author: Paul Nord

Subject: Re: Simple Rail Gun

Post:


--Apple-Mail-34-366524947
Content-Transfer-Encoding: quoted-printable
Content-Type: text/plain;
charset=us-ascii

Thanks Urs. That would surely be more dramatic.

But I still don't understand why Dave Kardelis' setup can roll both =
ways? I thought this was just the interaction of the field produced by =
the current in the rails with the field produced by the current in the =
cross bar. But that should only move in one direction. My setup moves =
in the direction I start it rolling in.

Paul


On Dec 12, 2010, at 3:24 PM, Urs Lauterburg wrote:

> 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.
>=20
> Regards form over here
>=20
> Urs
>=20
> Urs Lauterburg
> Physics demonstrator
> Physikalisches Institut
> University of Bern
> Switzerland
>=20
>> Ok Dave,
>>=20
>> I just tried it.
>>=20
>> My little battery charger trips off after a few seconds. And it =
doesn't have enough power to get the roller started by itself.
>>=20
>> 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.
>>=20
>> 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?
>>=20
>> Paul
>>=20
>>=20
>> On Nov 17, 2010, at 11:51 AM, david kardelis wrote:
>>=20
>>> Adam asked about my rail gun.
>>>=20
>>> 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.
>>>=20
>>> The power supply is a emergency jumper battery , one lead hooked to =
each rod on the table, see the thread on power supplies.
>>>=20
>>> Flip the switch and the rod rolls.
>>>=20
>>> 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
>>>=20
>>> Here is a video on Photobucket I took quickly this morning
>>>=20
>>>=20
>>> =
http://s366.photobucket.com/albums/oo108/dkardelis/Rail%20Gun/?action=3Dvi=
ewĄt=3D003.mp4
>>>=20
>>>=20
>>>=20
>>> 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,
>>>=20
>>> dave
>=20
>=20


--Apple-Mail-34-366524947
Content-Transfer-Encoding: quoted-printable
Content-Type: text/html;
charset=us-ascii

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 pointsHere is a video on =
Photobucket I took quickly this morninghttp://s366.photobucket.com=
/albums/oo108/dkardelis/Rail%20Gun/?action=3Dview¤t=
=3D003.mp4I 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<=
br =
class=3D"Apple-interchange-newline">=

--Apple-Mail-34-366524947--

Back