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Re: [Phys-l] x-ray machine

On Jul 8, 2009, at 12:27 PM, Roger Haar wrote:

Hi,

An electron gun is not Ohmic. The number of electrons per second
depends on the filament temperature and the extraction potential.
Only after this do the electrons "feel" the main accelerating voltage.
Changing this potential by an order of magnitude will do little to
change the number of electrons per second.

Yes, a vacuum diode is not ohmic; kinetic energy gained by electrons is turned into thermal energy at the anode, and not via multiple collisions with the medium between the electrodes. But changing the potential difference between the electrodes will change the current.

- - - - - - - - - - - - - -
Ludwik Kowalski, a retired physics teacher and an amateur journalist. Updated links to publications and reviews are at:

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

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