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spamtrap1888
Guest
Wed Jan 25, 2012 8:20 am
On Jan 24, 7:32 am, "Tom Del Rosso" <td...@verizon.net.invalid> wrote:
Quote:
spamtrap1888 wrote:
On Jan 23, 1:39 pm, "Tom Del Rosso" <td...@verizon.net.invalid> wrote:
spamtrap1888 wrote:
Let people get a good working understanding of things before you
drown them with abstractions. Thank goodness when I first became
interested in electronics, no one sat me down and emphasized the
difference between the abvolt and the statvolt.
I didn't say anything like that at all. I said resistance is
defined in terms of voltage and current, not the other way around,
and if you aren't ready to define voltage then just don't do it.
I don't think you sufficiently understand voltage. Explain to me the
difference between the abvolt and the statvolt, to prove me wrong.
They're just different units. Convert by multiplying by a constant. That's
all. It's like using the bell instead of the decibel or microns instead of
angstroms. That's not a big deal.
That's like saying a pound is a unit of mass. Try again.
Quote:
You don't start by teaching them about the leap second if you want
them to learn about the big hand and the little hand. Similarly they
don't need to know about how the earth wobbles on its access to know
when it's a quarter to five.
Which has nothing to do with avoiding teaching them something that's wrong.
Resistance is not a fundamental quantity. It's nothing but the ratio of
voltage and current, and only when measured in the absence of other factors
which are fundamental, so it's not something you should refer to when
explaining voltage.
What do you mean by fundamental property? Resistance (more precisely,
resistivity) is a materials property, as is potential difference. If I
make a cell (defining the voltage) and apply it to a hunk of material
(geometry plus a property of the material), that defines the current
that flows through the material.
Nelson
Guest
Wed Jan 25, 2012 5:09 pm
On Wed, 25 Jan 2012 01:20:52 -0500, spamtrap1888 wrote
(in article
<a5498ae8-19fa-42fd-8ca1-f6fbce9be30d_at_y5g2000pbk.googlegroups.com>):
Quote:
What do you mean by fundamental property? Resistance (more precisely,
resistivity) is a materials property
I could swear I recall deriving resistivity from the fundamental
properties of the material in question such as it's crystalline
structure, electron scattering cross-section, temperature, etc.
Quantum Thermodynamics or something. It was a very long time ago :-)
Since neither "voltage" nor "current" are inherent properties of
materials, resistivity would seem, to me at least, be the more
"fundamental" property.
As an analogy, you can define mass as the ratio of applied force to
acceleration, but I think most people would say that mass continues to
exist in the absence of force and acceleration and hence is a
fundamental property.
--
Nelson
Ian Field
Guest
Wed Feb 01, 2012 7:25 pm
"Woei Shyang" <nntp-terranews_at_w.woeishyang.com> wrote in message
news:2012012010200729084-nntpterranews_at_wwoeishyangcom...
Quote:
Hi,
I'm completely new to electronics, but I'd like to get started.
Perhaps it is just me getting tired of this wasteful culture where devices
are disposable, or just me being a tightwad, but I'd really love to learn
how to repair my own stuff, and know how various little DIY projects
actually work as opposed to putting them blindly together.
Are there any books that you guys might recommend to help me get started?
I've always been a software person by training and trade, so you can say I
have absolutely no background in this, except for being a geek.
Thanks for any tips and recommendations :)
The group: alt.binaries.e-book.technical has the book; Starting Electronics
4th ed K. brindley Newnes 2011 you can download free right now.
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