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Re: shadow mask



probably most materials have too high a coefficient of thermal expansion -- hence the
use of invar. A large % of the electron beam is intercepted by the mask.

bc

Mark Sylvester wrote:

A question that has lurked in the back of my mind for many years:

As I understand it, the shadowmask just blocks the cathode rays so they
don't hit the wrong colour phosphor. So it needs to be electrically
conducting, but there's no reason for it to be ferromagnetic, especially
since it doesn't work properly when it gets magnetized. So why then is it
not made of some non-magnetizable material?

Mark

At 20:38 20/11/02 -0800, you wrote:
Use a magnetic recording tape bulk demagnetizer if you don't have in you
lab a high
inductance coil air core coil, e.g. the coil for a Busch apparatus. (a
ferromagnetic
core will ensure demagnetization). Use a Variac if it doesn't have enuff L to
prevent overheating. Put a ball next to the core (or the open end of the
coil) with
max. safe current. remove slowly, then shut off pwr.

bc who had to demagnetize a shadow mask this way.

David Abineri wrote:

The steel spheres in the Newton's Cradle I have are now magnetized be
being too close to a powerful magnet. While this produces some
interesting variations of the cradle's normal operation, I would prefer
non magnetic spheres.

Is there a convenient way to demagnetize a sphere?

Thanks, David Abineri

--
David Abineri
dabineri@choice.net

This posting is the position of the writer, not that of SUNY-BSC, NAU
or the AAPT.

This posting is the position of the writer, not that of SUNY-BSC, NAU or
the AAPT.

Mark Sylvester
UWCAd
Duino Trieste Italy

This posting is the position of the writer, not that of SUNY-BSC, NAU or the AAPT.

This posting is the position of the writer, not that of SUNY-BSC, NAU or the AAPT.