Date: Sun, 12 Dec 2010 20:12:17
Author: Paul Nord
Subject: Re: Simple Rail Gun
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.
On Dec 12, 2010, at 3:24 PM, Urs Lauterburg wrote:
> 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 Lauterburg
> Physics demonstrator
> Physikalisches Institut
> University of Bern
>> 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?
>> 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
>>> 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,
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=
=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 =