Interesting story! I'd like to have a shot at teaching high school kids
someday.
I think you are thinking of "magneto-striction"- this is the phenomena
that causes transformers to hum, wires to vibrate etc... it is the
movement (vibration) of metal due to current flow (if memory serves
correctly). It is an important element of the design of the Magneto
Resistive head used in todays hard disk drives (and other storage
devices).
Electromigration is actually movement of metal from "here" to "there". It
can cause a wire to actually get thinner on one side and fatter on the
other. I don't know the actual physics behind it... I assume it has
something to do with what happens to the metal atoms when a ton of
electrons get moved through them.
It is a very real phenomena though in IC design.
Have you ever heard of Ivor Catt? He has a very bizarre notion about
current flow and charge in capacitors etc... I started to read his stuff
but became afraid that it would "mess me up".
Have a great night.
________________________________________________
Kevin Vannorsdel IBM Arm Electronics Development
408-256-6492 Tie 276-6492 kv@... KF6YCI
Please respond to Electronics_101@...
To: Electronics_101@...
cc:
Subject: Re: [Electronics_101] Re: Fuses vs. resistors
Kevin,
Fuses have resistance, that is true.
Yes and I realized that I had misspoken right away. That's what comes when
you
spend seventeen year trying to teach students who don't the difference
between
a pot and a grid leak. (I had to say it that way, I read that once back
in
the vacuum tube days.) Anyway, I could tell my students transistors were
made
of bird doo doo and some of them would have believed me. In that situation
one
doesn't get tested, nor does one's thinking get challenged very often. I
recall being surprised when my fellow teacher said the the charge on a
capacitor is stored in the dielectric, not on the plates. And of course
it's
true, what I can't figure out is where it's stored in vacuum capacitors.
They
are used in high voltage circuits, in radio transmitters we sometimes have
problems with humidity causing caps. to arc.
I got my pride back when I explained that AM radio stations can modulate
above
+/- 5 kHz. He thought that the 10 kHz spacing that they were so limited.
But
stations are not assigned adjacent channels where they'd be close enough
to
interfere.
Have you guys ever heard of electro-migration? This is the movement of
metal due to current flow.
Is that when wires carrying high current sometimes vibrate?
It is a serious consideration in IC design. It is an interesting
concept...
but I think heat is the mechanism of fuse blowing anyway.
True but it makes sense that the fuze would have to have resistance since
with
none there'd be no heat and thus the fuze would not fuze. :-)
Jim
To unsubscribe from this group, send an email to:
Electronics_101-unsubscribe@...
Your use of Yahoo! Groups is subject to
