Re: [Phys-l] x-ray machine

[ludwik kowalski <kowalskil@mail.montclair.edu>]

On Jul 8, 2009, at 8:20 AM, Anthony Lapinski wrote:

> I saw a new dentist a few weeks ago. I could easily see the x-ray  
> from the
> chair, and wrote down some information. I often use "real"
> devices/appliances in my classes when discussing electricity, Ohm's  
> Law,
> etc.
>
> x-ray machine:
> 60 kV
> 7 mA
>
> Using Ohm's Law, we get:
>
> R = (60,000 V)/(0.007 A) = 8.57 x 106 ohms
>
> I thought this result was interesting -- either very high or Ohm's Law
> does not apply well in this case. Any ideas?



Why is 8.57 megaohms unexpected?
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Ludwik Kowalski, a retired physics teacher and an amateur journalist.  
Updated links  to publications and reviews are at:

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   http://csam.montclair.edu/~kowalski/revcom.html

Also an ESSAY ON ECONOMICS at: http://csam.montclair.edu/~kowalski/economy/essay9.html