Electro

It's taken me a long time, but I think I am finally beginning
to understand the various concepts related to electricity. And
I mean long, with voltage and current longstanding enemies since
High School, and wattage on a hairdryer a mysterious outsider.

Electrical current comes down to electrons speeding along a wire. Direct
current is a circuit that starts at the positive end of a battery and ends at the
negative end. The battery runs a chemical reaction which soaks up the incoming
electrons  and makes them available anew at the positive end.  This is the
voltage of the circuit, in volts.

Electrons, then, are not going at or near the speed of light in a vacuum. They are
met with resistance, which must be overcome. The load of the circuit is what offsets the
voltage. It can consist of resistance elements either in series or parallel. The
fundamental relationship between these concepts is Ohm's Law. The reference definition
is that given to the current, in amperes, which is a coulomb(electrons)-second.

V = iR
Resistors pace the circuit; they are weighing-ins, but the current runs through.There
are also capacitors which might store current for some time. The unit is the farad,
which is a coulomb per volt.

Voltage, then,  equals current (in amperes) multiplied by resistance (in ohms). A coulomb
has so many electrons,(6.24 x 10^18 electrons, for a negative charge Coulomb)) and an
ampere is an available coulomb every second. Voltage is the derived notion of potential
difference between points on a wire.

So what about my hairdryer!?

p = Vi
The power made available to appliances is in watts, which are joules per second. A
joule, it will be remembered, is a unit of work or energy:(It is a newton-meter). The
more watts, the more work performed per unit of time. It is a measure of dissipation
of energy with respect to the circuit.

In point of fact, a hairdryer would not run on a direct circuit. A small light bulb would:
alternative current to come. Small hint: there is a transformer involved, which uses the
magnetic force around a coiled wire to transfer current to another coil.

source: Khan Academy, with back-up readings from Wikipedia.

                                                *     *     *
In a direct circuit created by a battery, electrons are actually flowing from the negative pole
to the positive; but charge is still considered to move from positive to negative. (There are
circuits were it is a positive charge that moves).

The math works out the same, because electricity is a field concept, and voltage refers to
potential difference.

http://www.physics4kids.com/files/elec_intro.html