the tater is one part, the electrolyte (an ionic solution).
a battery needs two dissimilar metals (not any metal but two that have a potential electrochemical relationship) which are not touching and electrolyte (which allows chemical ions to flow through it).
Others have already introduced the water pipes analogy for voltage, current (aka amperage, since it’s measured in amps) and resistance (measured in ohms), but I don’t think anyone has yet mentioned the relationship between them. The voltage is equal to the current times the resistance. So if you have a circuit (or water pipe) and you have a given amount of voltage (or pressure) on it, and you change the resistance, when you’ve got less resistance, you’ve got more current (or water flow). If you have a given amount of resistance and you increase the voltage (or pressure), that also gives you more current (or water flow).
And others have also already mentioned that power is voltage times current, but more should be said about what “power” is. Power is how much energy you can exert per time. Even a low-power motor can do a lot of work (exert a lot of energy) if you leave it running long enough. One horsepower is about 746 watts, so if you have a motor that draws a current of 6.8 amps at 110 volts, it can do about the same amount of work in the same amount of time as a horse can.
An electrode is basically the end of a wire, where electricity is collected or dispersed. 
Anode and cathode are types of electrodes; one colects electricity, the other disperses it. In a battery, you have both, one on either side of the pile of stuff that is hosting the chemical reaction that pushes the electricity along.
You may also hear terms like diode, triode, pentode, etc. These date from the days of electronic “tubes”, wich were circuit components that looked like incandescent light bulbs, but had a lot more stuff in them.
The ‘ode’ referred to an electrode; the ‘di’, ‘tri’, etc, counted the number of electrodes sticking into the tube. The tube was empty of air, so there was nothing to keep electicity from flying across the space between electrodes… assuming the electrodes were warm enough to let the elecricity jump free in a controled way. (This is why tubes had heaters as well. These weren’t counted among the electrodes.)
A diode had two electrodes. It could be set up to pass electricity one way, but not the other, like a check valve for water. This turned out to be extremely useful, and led to the British name for tubes: valves.
By applying changing voltages to one of the electrodes of a tube with three or more electrodes, you could control the flow of electricity between other electrodes. That is, you could use a small electrical signal to make changes in a larger signal. And thus, the amplifier was born.
Later, tubes were replaced by much smaller ‘solid-state’ compoents, but the name ‘diode’ for the one-way component was retained.
EE checking in… The usual analogy is to water and for non-reactive circuits (resistive = no capacitors or inductors) it’s not bad.
Voltage (volts) is analogous to pressure, Current (amps) is analogous to volume or flow. You can have large voltage and small current (think a water pick) or you can have low voltage and high current (think lazy river). You need both to do work and in fact to make Power (watts) you simply multiply them: P = V * I.
Now, when dealing with motors and some other devices, once you start reading labels, you will notice that Power is sometimes referred to as Volt-Amps rather than resistance. This is due to Power Factor. This is where the analogy begins to break down as we are leaving the realm of resistive circuits and entering a realm where there are things like capacitors and inductors that can store energy and return it later (often within the same alternating cycle). This is also where complex numbers (real plus imaginary) are used to represent electrical properties. Real for electrons that delivered and imaginary for electrons that come during one part of the AC and leave during another. This imaginary flow is still important as they represent flow in the wires and circuitry (cables, cords, outlets, etc.) must be capable of handling them. But we’ll leave all that aside for now.
Energy (joules) is power multiplied by (integrated over) time. E = P * T if you will. At the end of every month, you pay for the energy you used. You write a check for so many watt-hours. It isn’t just how powerful that light bulb is but also how many hours you ran it.
Resistance (ohm) is analogous to friction and relates to voltage and current like so: V = I * R. So if your voltage source is constant and you double the resistance (R), you halve the current (I). If your resistance is constant and you double the voltage, you double the current. This formula is called Ohm’s Law.
If you string two resistors together in series, the resistance is increased. Each electron must flow through first one and then the other. So the total resistance is Rt = R1 + R2. If you connect them in parallel, the resistance is reduced. Each electron has a “choice.” One can “choose” to flow through one resistor and the next electron can flow through the next. The reciprocal of the total (equivalent) resistance is equal to the sum of the reciprocals of the two resistors: 1/Rt = 1/R1 + 1/R2. For identical resistors this works out to half, e.g. Two eight ohm resistors in parallel looks the same to the voltage source as a single four ohm resistor.
I think this answers your questions. Wiki or a decent introductory book on the subject should provide more if you still have interest. Wikibooks has a completed text on circuit theory: Circuit Theory - Wikibooks, open books for an open world.
Thank you thank you thank you! I know you probably had better things to do with your day, all of you, than write Electricity for Dummies. But I really think I got it. At least, I got it more than I did this morning! A small portion of ignorance has been fought today.
Now try to figure out the difference between neutral and ground. I still don’t really get that.
In an electrical circuit there must be a return path or there’s no circuit. The Neutral carries this current by design. A Ground should only carry current in the event of a fault, e.g. to keep a chassis from becoming hot. There’s a pretty good wiki entry on the subject. You can use earth ground as a return but there are safety and performance issues. See also Single wire telephones.
The neutral wire is the return line for used electricity, and the ground wire is connected directly to the ground point, which is the reference point from which all voltages are measured.
Ground wires are a safety measure. They are like spillways to catch unplanned floods of electricity that break loose from the normal channels. The ground point they are connected to in a building is often an actual copper rod pounded into the ground outside the building.
Meanwhile, for the neutral wire, imagine the battery as a pump. The supply wire (called the hot wire) is the pipe from the pump to your equipment. The neutral wire is the return line from the equipment back to the pump. (And the ground line is the drain from the tray under the equipment that catches all the drippings and condensation.)
That’s for DC. For AC, imagine the water kind of sloshing back and forth in the pipes. The water analogy starts to break down here.
A lot of old schematics used the same symbol for battery and capacitor. And occasionally they function similarly in a circuit, like in a car’s electrical system. The Leyden Jar seems to be a capacitor, and apparently used as an early form of electical ‘storage’ before chemical batteries, and apparently called a ‘battery’, I heard because ‘batteries’ of Leyden Jars were sometimes connected. It is surprising to hear this misconception persists though. Do people with any real background still make this mistake? I know people with no formal training that have just fooled around with components to make buzzers and flash LEDs that seem to know the difference. Do you think this idea is out there in print somewhere?
OK, first off, voltage itself doesn’t really matter, just voltage difference. Usually, you pick some point in your circuit and call that “zero volts”, but that’s just a convenience. It’s a lot like elevation that way: If you ask me how high up I am, I could tell you that I’m on a chair about two feet above the floor (and consider something on the floor to be at “zero height”), or I could tell you that I’m about 20 feet above ground level (and consider something sitting on the ground outside to be “zero height”), or I could tell you that I’m nine tenths of a mile above sea level (and consider something at sea level to be “zero height”). Any of those are valid, and I could think of plenty of other ways to measure height, too. But no matter where I set my zero, if you ask me how much higher up I am than where I parked my bike (which is relevant when I’m going up the stairs), the answer to that one is the same.
OK, now, for a circuit in your walls: The wires end up ultimately going to two points on a transformer, and the potential difference (voltage) between those two points is (typically, in the US) 110 volts. If you follow the circuit all the way through, over the course of the entire circuit, that’s how much the voltage changes. Now, voltage hardly changes much at all from one point in a conductor to another, so essentially all of that voltage drop is in the light bulb or whatever. In the water analogy, this would be like a river that flows almost completely horizontally for a while, then going over a waterfall, then flowing horizontally again. There’s the same number of gallons per second going past at any point in the river (translation: same current at every point in the circuit), but there’s a much bigger drop at some parts than others. And on the mostly level parts, you can say that one part is at one height, and another part is at another height.
Now, whenever there’s a net drop from one point to another, and a path between them, electricity/water will flow. There are a lot of things in a house we don’t want electricity flowing through (like, say, you), so you want to make sure everything in the house that you can touch is at the same voltage. You do this by connecting everything to ground wires, and connecting the ground wires to the Earth. The ground wire is then like a canal, or a calm lake: Every point on it is at the same height, and there isn’t really any water flowing anywhere, it’s just sitting there. And to make sure that no water ends up flowing from your canal system to the ocean, you put the height of your canals at sea level.
OK, back to those wires that are powering your light bulb: All that really matters is that there be a voltage difference between them, and your light bulb would work just fine if one wire were 1,000,000 volts above ground, and the other was 1,000,110 volts above. In practice, though, it’s easiest to have one wire at 0 volts (that is, at the same voltage as ground) and the other one at 110 volts above ground. The wire that’s at the same voltage as ground is the neutral wire, and the other one is the hot wire. But even though both the neutral and the ground are at the same voltage, they are not the same, because the ground wire is a canal with essentially no flow at all in it, while the neutral is a river with a large flow.
Of course, an SDMB thread on a general topic is never just for one person. Lots of people besides the OP are certain to read it.
GAAH!
The symbol for a battery and a capacitor are NOT the same. The Battery has a long plate and a short plate - a capacitor has two equal-sized plates (or one curved).
And they DO NOT FUNCTION the same (especially in a car).
Is there no end to the quibbling? I did not say the symbols were the same, I said old schematics ‘used the same symbol’, and I said ‘function similarly’ not ‘function the same’. Car electrical systems use the battery as a simple way to provide steady voltage instead of employing more complex circuitry. How much qualification is necessary to hold a reasonable discussion about anything? Do you have any information about the extent of the misconception noted, and where it comes from?
Missed the edit window. ‘function similarly’ is a poor choice of words. ‘perform a similar function’ would have been better.
I’ve recommended this before, but back when I was teaching introductory physics, one of the best resources I ever came across for simple explanations of electricity were the articles written by the SDMB’s own Bill Beaty. I would start here.
Eh, be very, very careful with that site. He’s got some good stuff there, and then some gee-whiz stuff that isn’t really explained, and then a whole lot of crackpottery.
I think one of the best online textbooks is All About Circuits. It’s probably a bit more advanced than absolute beginner but it does take a fairly simple approach (I’d consider it about advanced high-school or very basic college level. It doesn’t go too far into math that I’ve seen, although I haven’t read it all.)
One other thing I’d say is to go beyond thinking of electricity as merely the flow of electrons and think of it as a flow of charge, or even better - energy which is mediated by charges. Electricity as ‘electron flow’ isn’t entirely wrong but I feel it only works up to a point.
So…amps vs. volts.
I’ve always heard that it’s the amps that you have to worry about with regard to the danger involved in working with electricity.
Or is it the volts?
Anyone wanna clear this up?
(In other words, the saying I’ve heard is “It’s the (amps)(volts)* that can kill ya”.
*choose one
Data for determining the severity of electrocution use current (in milliamps) as the independent variable. As an example, you begin to perceive the current at around 4 mA, and experience muscular contractions at around 20 mA.
If most power supplies you encounter were constant current type, then the current through your body would be solely determined by the amount of current produced by the power supply. But constant current power supplies are rare. Almost all power supplies you encounter are constant voltage, not constant current type. Therefore, the current through your body is a function of two things: 1) The voltage produced by the power supply, and 2) your body resistance. The higher the voltage produced by the power supply, the higher the current through your body.
So is it the volts or the amps that kill you? Well, technically speaking it is the amount of current. But you first need a voltage in order for current to flow through your body.
It depends on whether the source can provide enough current to kill you.
It’s possible to generate extremely high voltages that are perfectly safe for most people because they will collapse if an amount of current that comes anywhere near that required to kill a normal person is drawn.
On the other hand, if the source into which you come into contact can provide the current required to kill you it’s the voltage you need to worry about because that’s what causes the current to flow.
For example, you could have a 5v source that could provide 1000 amps and it would be safe to touch.
Yet a source that was at 100v and could only provide 5 milliamps at that voltage could kill you.
So, really, unless you don’t mind getting shocks from non lethal high voltage equipment, it really is the voltage that you should be worrying about.