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Adam and Eve
What makes your brain tick?
According to researchers, the parts of your body, if you don't use it you lose
it, particularly your brain. The more you use it, the more logic & brainier you
are. Could that be true?
AC, DC, Volts, and Watts, what do they mean?
Let alone Amperes, Coulombs, Currents, Capacitors and
Ohms...
There's also the Electron, Electric, Electrode, Electrostatic and
Dielectric, enough to made your hair stand on ends... and that's exactly what
they do (the potential differences) -- the Van de Graaff generator for example,
named after the guy who invented the gadget.
To understand how the Van de Graaff's gadget made your hair stand on ends, we need to understand static
electricity -- the shock we all experienced on dry winter days.
Electrons (static electricity) build up in our body and cause
sparks to jump when we touch metal door handles, the familiar sound of spark we see,
hear and feel.
If you rub a ballroom on your head, the ballroom picks up tens of 1,000s of negative
electron charges, to understand all that, we need to think about atoms that make
up our world !!!
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It's not a bad idea to use our world as an
analogy to atoms - the red core as neutrons, the molten (orange bit) as
protons(+)
and the outer shell as electrons (-). |
All matter is made up of atoms, which are themselves made
up of charged particles.
Atoms have a nucleus consisting of neutrons (neutral) and
protons (positive), they also have a surrounding 'shell' that made up the electrons
(negative).
Typically, matter is neutrally charged -- meaning that the number of electrons and
protons are the same.
If an atom has more electrons than protons, it is
negatively charged, and if it has more protons than electrons, it is positively
charged. (Think of our earth crust and the molten balancing each other
helps).
Some atoms hold on with their electrons petty tight while others can't hold
on too well. How good atoms hold on with their electrons depends on matters
-- if a material is more apt to
give up electrons when in touch with each other, it is more positively charged.
And if a material is more apt to
capture electrons when in contact with each other, it is more negatively
charged.
Bonding
When two non-conducting materials come into contact -- a
chemical bond known as adhesion is formed, depending on the
type of materials, one
may capture some electrons from the other -- while separated from each other
has a charge imbalance.
Materials that capture electrons are negatively charged and materials that
lost electrons are positively charged -- this charge
imbalance is where static electricity comes from.
Static Electricity
The term static is
really deceptive, because it implies no motion, but in reality it is common and necessary for charge imbalances to flow. The spark you feel when you
touch a door knob is an example of such electrons flows.
If the weather is humid, the moisture coats the surface of the material,
providing a low-resistance path for electron flow, this path allows the charges
to recombine and thus neutralize the charge imbalance.
On dry winter days
(heating dry up the place)
charges can build up from your nylon carpet to 10's of thousands of electron volts.
In 1931, physicist Robert Jemison Van de Graaff demonstrated his device that bear his name,
the generator can produce extremely high voltages -- up to 20 million electron
volts, that high energy was needed for early days particle accelerator test,
the ability to create high-energy collisions is the foundation of particle and nuclear
physics.
Serial vs. Parallel
When you put a load on a Van de Graaff generator, the current (ampere) remains
the same, it's voltage varies with the load. A good example is your car
battery which produce about 12.6 volts when new (that's 12.6 joules of
energy are supplied to each coulomb of charge that is made to flow in the
circuit).
If you turn on the headlights (which say require10 amps) and the windscreen wipers
(another 4 amps) and then check your battery voltage, you will see that the
voltage remains relatively unchanged regardless of what you turn on and off the
same time -- now that's DC (direct current) for you, and arranged in parallel, not serial (meaning one after the other).
What's Ohms, Amperes, Coulombs, and Currents?
Now that you know currents (charges) can go either way, that means we can
alternate them -- that's AC (alternating current) to you, and as the name
implies that electrons moved first in one direction and then in the opposite
direction, alternating to and fro at relatively fixed positions.
Well, you can alternate the direction of voltages at the energy source, most
domestic voltages and currents alternate @ a frequency of about 60 cycles per
second -- that's 60-hertz current. Some countries choose 50-hertz or
30-hertz and even 25-hertz for safety reasons.
Electron
Electrons do not travel through a wire in your AC circuit, instead
they vibrate to and fro at relatively fixed positions. When you
switch the light on energy is carried by the electric field and causes vibratory
motion of the electrons that already exist in the lamp filament.
Most of this electric energy
is transformed to heat, and while some takes the form of light, your power utility
companies DO NOT sell electrons -- they sell energy and you supply the electrons.
Current
Our computers prefer direct current (DC), the flow of charges in one
direction -- electrons move from the repelling negative side towards the
attracting positive side, making (programming) this page on your screen
possible, also allows you to use lap-top (battery power) computers.
The familiar
3-point plugs with the top point connect to earth, and the other
two points -- one of them is live, the other neutral.
Electrons travel in our circuit at nearly the speed of light, the conducting
wires act as a guide for the electron flows, but some how, some of these guys
(electrons) bump on to the anchored ions along the way, and
lose their kinetic energy -- thus our computers (or wires) become hot.
Ohm
The increased temperature means increased resistance, some materials reach
zero at low temperatures, these are called superconductors.
In 1826, the German
physicist named Georg Simon Ohm pointed out a simple and very important
relationship among voltage, current and resistance.
And you named his brain power the Ohm's law -- I don't see what has it got to do
with the Greek !!! But the Greek letter (Ω) omega is commonly applied to
Ohm's symbol.
Ohm's law states that the amount of current in a circuit is directly
proportional to the voltage applied across the circuit, and is inversely
proportional to the resistance of the circuit -- in other word:
Current = Voltage / Resistance.
Or in formal language: Amperes = Volts / Ohms.
Generators separate charge by electromagnetic induction, this energy per charge
provides the differences in potential (voltage) that provides the 'electrical
pressure' to move electrons through the circuits.
Joules
The unit of electric potential (voltage) is the volt, the power supply
in your PC reduces the electrical pressure of AC (alternating current of
60-hertz) to 12 volts in DC (direct current), that's 12 joules
of energy are supplied to each coulomb of charge that is made to flow in
your PC circuit.
Ampere & Coulomb
Just as water current is the flow of H2O
molecules, electric current is simply the flow of (energy) electric charge. The rate of
electrical flow is measured in ampere - an Amp is the rate of flow
1 coulomb of charge per second, and 1 coulomb (the standard unit of charge) is
the electric charge of 6.24 trillion-billion electrons -- 12 amperes x 6.24x1018 is awful lot of electrons flowing through our PCs.
The concept of electric potential is measured in volts, and this
voltage acts like an 'electrical pressure' that can produce a flow of charge, or
current measured in amperes (simply Amps or abbreviated as A), and the resistance that restrains this flow
-- is measured in Ohm's (Ω).
The rate at which energy is transferred by electric current (it's power) is
measured in Watts (W).
Author
10/02/2010
Mantra: You can't cure brain death but you can prevent
it.
Notes:
(1) The Greek letter omega (Ω) is commonly used as the
symbol for Ohm
(2) The word electron
came from Greek meaning amber
(3) Electrostatic charges are not caused by friction, dragging your feet on the
carpet will build up a charge, electrostatics and friction are related in that
they both are products of adhesion.
(4) Dielectric is a semi-insulating material.
(5) One coulomb (C) is equal to 6.241 x 1018 of electrons per second.
(6) Capacitors - A small device which stores electrical charges.
What's the moral in these stories?
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