Welcome to ECN!
Got quite a few good questions there! I'll try to answer for you with some concise and simple explanations.
1:
what makes a magnet attract?
In the 3 magnetic elements (Iron, Nickel and Cobalt), the atomic structure (lattice) is arranged (or becomes arranged) in straight lines. The atoms line up kind of in a "Hand-in-Hand" fashion, which results in a circulating flow - hence the magnetic attraction.
2:
how does a magnetic circuit work
When electrons flow in a conductor, there is a resulting Magnetic field produced (at a right angle to the flow).
In the core of a transformer, or a solenoid's core, the winding produces a magnetic flux in the core - via Induction. The magnetic flow acts similar to the electrical flow, and changes are made correspondingly.
3:
what causes the electric force in a circuit
Simplest answer: A difference in Potential.
Simple example: Pick up a rock off the ground. Hold it above the ground. The rock can fall to the ground - hence there is a Potential Difference between the rock and the ground.
4:
when electricity comes out of the wall or a battery, does it flow out of the positive,through the circuits of the appliance, then back into the negitive
For DC circuits (like a car battery or a drycell), the current flows from Negative Polarity (Cathode), through the load device (like an Incandescent Lamp), then to the Positive Polarity (Anode).
The current flowing is in the form of Electrons, which are "-" charges.
In actuality, there are "+" charged "Holes" flowing out of the Anode towards the Cathode, and the Electrons "Fall" into the holes - but that's a little advanced for now!
DC is Direct Current, meaning the current flows in a single direction with a nearly fixed amplitude.
For AC, there is no fixed Polarity, so it is safe to say that current flows in BOTH directions.
On a simple 2 wire circuit, current flows in one direction for 1/2 of a cycle, then that same current reverses direction and flows the other way for the remaining 1/2 of the cycle.
Think of how a See-Saw reciprocates back and forth, and you can invision the current flowing in an AC circuit.
Another visual method is the way a Sawsall blade recips back and forth, also a piston / connecting rod and crankshaft for an internal combustion engine.
AC stands for Alternating Current, and has no fixed Polarity.
5:
Briefly described above. This is an indepth subject, so best for you to study this one on your own with some very good manuals!
AC and DC are two completely different Animals! Even though they are in basic sense very similar and can use similar basic equations / formulas / circuit elements, AC has SOOOOOOOOOO many more advanced items which makes it very different - and extremely complex!
Much easier to grasp the basics on your own via books, then we can go into more detail on line.
I could try to toss out some AC basics, but it is very difficult to use text in describing AC basics.
Check out some of the items posted in the Technical Reference section, as they may be a little help or inspiration.
Scott35
p.s. needed to edit bad spelling!
[This message has been edited by Scott35 (edited 06-08-2003).]
