"Phil Scott" wrote in message
...

If you *get inside* a soldered or tinned end and think of the strands,
how the electricity actually *moves* then the concept begins to open up.
Electricity travels on the surface of the circuitry. For wires the area
of travel is the surface area of the cable, Length*Pi*diameter. Adding
solder changes the surface areas and if you blob the terminal rather than
tin the strands you change the surface area of the wire and hence the
physical characteristics of the cable.


Thats interesting... and at the least reasonably valid possibly. Id like
to hear more about that.


I'll throw some ideas at you, and some titles, my apologies, I don't have
any net citations (I tend to learn from books especially if it's scientific
technical), but I'll quote from my textbooks. More if you wish.

Think of rubbing an ebonite rod with dry fur.

"An ebonite rod which has been rubbed with dry fur attracts light bodies,
such as small pieces of paper, and it repels another rod which has been
treated in the ame way. A glass rod which has been rubbed with silk also
attracts light bodies, repels another glass rod which has been similarly
rubbed, and attracts an ebonite rod which has been rubbed with fur."

"A negative charge placed at any point on an insulated conductor repels
electrons in the material to all parts of the surface, while a positive
charge at any point attracts electrons from all parts. That is, a charge
placed anywhere on a conductor effectively spreads all over it, because the
electrons in the material itself are free to move. Insulators do not contain
free electrons, and electrons are not easily seperated from their positive
nuclei; so a charge placed on an insulator does nt spread over its surface.
Ebonite, glass, mica, paraffin wax, sulphur, and dry silk are among the best
insulators. Dry air and dry gases generally are good insulators in ordinary
circumstances; moisture in a gas or on the surface of a solid reduces the
insulating properties greatly. Electric forces act *through* (itallicised in
the text) insulators, which when spoken of in this connection are called
*dielectrics* (itallicised in the text)."


Think of the Gold Leaf Electroscope.

Charging by induction.

The Electrophorus.

Faradsy's "ice-pail" experiment.

Distribution of potential and charge over the surface of a conductor.

Capacity. Condensors.

Displacement currents.
"Maxwell defined the displacement current as *the quantity of
electricity which is caused to pass normally through one square centimetre
of the dielectric on account of the electric intensity*. If there is a
surface density of charge of Q ESU per sq. cm. on the plate A, a charge Q
moves across each square centimetre of the dielectric from A to Z, so *the
displacement D in the medium is equal to the surface density Q on the
charged plate*. The electric intensity, as the cause of the displacement, is
analogous to mechanical stress, and the displacement to mechanical strain.
The energy stored in unit volume of a mechanically strained elastic medium
is 1/2*(stressxstrain). The electrical energy stored in unit volume of the
medium is similarly 1/2x(intensityxdisplacement), or 1/2ED."

(confuses my concept somewhat)

Wimhurst machine.

Van de Graff generator.

Gauss's Theorem.

- Intensity due to an isolated charge conducting sphere (pg 35)

- Intensity close to the surface of a conductor (36)

- Force on the surface of a charged conductor (36)
"The charge resides entirely on the surface, and the reason why
the charge on any element is held there is that all the other charges from
all over the conductor combine to produce an intensity directed outwards
which holds it there. Further, as there is no intensity inside the
conductor, the intensity due to the charge on the element must just cancel
out that due to all the other charges at points inside the surface." goes on
to say "... It remains to reconcile the two results..."


Law of inverse squares.

Definition of the absolute EMU of current "that current which, flowing in an
arc 1cm. long of a circle of 1cm. radius, produces at the centre of the
circel an intensity of 1 oersted."
"The practical unit of current, called the ampere, is one-tenth of the
absolute unit. " cf pg(110 and 323)


Heating effect of a current.

Mechanical equivalent of heat.

Electric Lamps and heaters. (178)

Electrolysis. Electroplating. (cf witchcraft, lol)


Textbook of electricity and magnetism. G.R. Noakes MA (Oxon) F.Inst.P.

(a man who could express himself without using the word '****tard' or
'retard' or any other derogation I can find).

London, Macmillan. 3rd edition. 1956. Maybe the times have changed.

A study of the fuse would likely be good.

Oh and Roy, before you explode like a fool, you are sacked as a tutor. Maybe
I'll write you a new standard.


I feel sorry for the Original Poster, the ****e posted in here so far may
have scard him off for life. "wow, look what I've done now" he thinks as the
bar-room is trashed and the ladies run for cover.




in the controls business of course the amperage very small so thats not an
issue and we can solder the ends of the wire.

The idea you present on current flow being possibly less at a soldered in
connection would make a good google search.... If I find anything on that
I will post it.


I'd be interested too, I posted what I said because of studies I did while
working for Philips components; working making magnets with some really
illuminating chemicals, the stuff used was hydrophilic and pyrophoric, it
combusted when we poured Vmto onto it! They use our little magnets inside
computer Hard Dives now.
The studies weren't reqired for the job, but they were interesting none the
less.


--
Billy H

The spirit is not the letter, 2 corinthians 3,6

When a ship heels at sea she must give equal
draught to lee as she takes to windward.
Else she becomes unstable fore and aft, and
may become quite sickly.

Nantes-Howard Naval Architecture 'n' Terrestrial Engineering Services.

A subsidiary of Howard Engineering.
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