[Phys-L] Re: electricity demo apparatus and radiation

[Bernard Cleyet <anngeorg@PACBELL.NET>]

Yes.

Back in the fifties, I made a radio graph using a spark coil similar to
the Ford model A/T type, but much bigger.  I still have the negative of
a mechanical pencil.  The X-ray tube was a three element (electrode)
cold cathode demo. one still found in teaching store rooms (HS and
college).  My memory is a bit dim, but I'm certain the exposure was
certainly less than a few mins.  Therefore, I 'd say there was a
dangerous amount of scattered radiation.  My friend at North HS has such
a tube and he uses a Tesla (hand held self contained) to demo. it, I
think.  I'll check w/ him.

Is the R-meter an electrometer type?

bc

Karl Trappe wrote:

> What follows is an old discussion about the safety of Cathode Ray
> Tubes when used in conjunction with the Leybold spark coil.  The air
> stopping, which John Denker mentioned was recognized in one of the
> replies. I do not know what difference the use of the tesla may make.
> Perhaps its not the high frequency due to the intermittent nature of
> the device, but the far lesser current available due to the air gap.
> I vaguely recall that the hand held tesla's were "safer".  I may be
> recalling incorrectly.  Karl
>
> Sam,
>
> If you want accurate measurements of low energy x-rays see if you can find a
> Victoreen R-meter.
>
> Also remember the issue isn't a one time use; what concerned me in my work
> was that I would be setting up this equipment several times a year and the
> accumulated dose. That said the risk is still not that great as risks go.
> Being real close to the hottest tube I had for a minute would be like
> smoking a pack of cigarettes riskwise.
>
> Cliff
>
> ----- Original Message -----
> From: "Sam Sampere" <sampere@physics.syr.edu>
> To: <tap-l@listproc.appstate.edu>
> Sent: Thursday, October 10, 2002 2:21 PM
> Subject: Re: Cathode ray tubes for demos
>
>
>
>
> > I think you need to be more careful here.  We all do for that matter.
> Remember,
>
>
> > we're the pros and we need to KNOW, not just think.  I don't know, so I'm
> looking
cut
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