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I am a little confused about just how it works with regard to current flow. As far as I know, current flows from the negative pole to the positive, because electrons are attracted to the positive source.

Looking at power lines, I know the voltage is "stepped down" from high voltage carrier lines, to substations, and stepped down again before it gets to a house. Every pole has a ground wire run into the earth, which is the negative. My question is, then isn't the truth that, since the ground is the negative end, that the electricity should be flowing in the opposite direction, and that the voltage is actually "stepped up"?

Also, the truth is that if you touch one wire and not the ground, you don't get zapped. If the current is coming from the ground, and not trying to get to the ground, why can we safely touch the bare ground wire on poles?

2007-11-15 06:06:40 · 5 answers · asked by messenger_of_the_void 2 in Science & Mathematics Physics

Ok, I knew the alternating current bit, just didn't understand that the direction of current actually oscillates...cool...

So in a DC situation like a car, with the negative battery being "ground" to the chassis (this is essentially where I got the ground-negative notion), is it more like I thought and the electrons just go from the chassis toward the positive end of the circuits, or is this a discrete concept that I'm missing?

2007-11-15 06:35:18 · update #1

5 answers

The first thing to note is that the vernacular "above", "below", and "step down" have different meanings than in conventional language.

Electrical "current" is a positive flow of electricity. It travels from positive to negative. (This is a convention: although electrons are responsible for the current, everything is mathematically consistent if you take a positive current flowing in the opposite direction of a negative current . . .)

The voltage being "stepped down" through a transformer means that the voltage AMPLITUDE is reduced, and has nothing with moving up or down.

Conventional AC ground is taken as earth ground, meaning that the electric potential of the ground lead is identical with the surrounding earth (e.g. ground), thus no current will ever flow from the ground into another object also at ground, e.g. in contact with the earth.

The "hot" AC wire alternates above and below ground, meaning that if you held on to the hot AC line and a metal pole stuck in the ground, you would have current pass through you and be shocked. Half of the time you will have current pulled through you from the ground to the hot line, and half the time current goes from the hot to the ground. This switching of current direction in AC is responsible for its characteristic feel.

Yes, in a car battery electrons flow from ground the the higher potential, usually 12V above ground. Once again, in this case the ground is externally held to ambient neutral (by having the ground in contact with the car). This is not quite as "true" a ground as earth ground--as you may know when you exit a modern car after driving some time you can sometimes get a nasty shock from the chassis. Your car itself gets charged from the wind and is not at true, or earth ground. Nonetheless, nothing changes with the operation of the electronics in the car since the high potential of the battery is 12V above the car's potential as it always has been. When speaking of this ground as a reference point for 0V, people refer to it as a "floating ground" meaning what you take to be a reference of 0V, may not necessarily be electrically neutral relative to the surroundings (or safe to touch.)

2007-11-15 06:16:48 · answer #1 · answered by supastremph 6 · 1 0

Ground is not negative. Ground is a reference that we use to define the quantity of 'zero volts'.

Anything with a higher concentration of free electrons would be considered negative with respect to ground. Anything with a lower concentration of free electrons would be positive. Yeah, it's backwards, it dates back to early days of electric research. Back then there was little knowledge of atomic theory, and the concept of the electron did not exist. They needed to label the voltage scale, and they guessed wrong.

The power delivered by the power company to your home is not considered positive or negative as it is AC, or alternating current. The voltage is actually a sine wave with spends equal time being positive or negative. These lines are generally considered "HOTS".

These sine waves are generated in three different phases of rotation and can be used separately with respect to ground, or in pairs depending on the needs of the device.

In an AC system, the electrons generally do not move. They vibrate back and forth.

As for being able to safely touch a single wire: This is true. Electricity flows in circuits. If the circuit is not complete, there will be no current flow and you are safe. You must be sufficiently insulated from ground or any other source that may complete a circuit.

2007-11-15 06:16:07 · answer #2 · answered by DT 4 · 1 0

"In scientific usage, a theory does not mean an unsubstantiated guess or hunch, as it often does in other contexts. A theory is a logically self-consistent model or framework for describing the behavior of a related set of natural or social phenomena. It originates from and/or is supported by experimental evidence (see scientific method). In this sense, a theory is a systematic and formalized expression of all previous observations that is predictive, logical and testable. In principle, scientific theories are always tentative, and subject to corrections or inclusion in a yet wider theory. Commonly, a large number of more specific hypotheses may be logically bound together by just one or two theories. As a general rule for use of the term, theories tend to deal with much broader sets of universals than do hypotheses, which ordinarily deal with much more specific sets of phenomena or specific applications of a theory."1 The word "theory" in common usage carries with it an implication that this idea you are putting forward is weak or poorly backed up. The difference is that in science this particular word does not give that implication. Some scientific theories have very strong reasons for us to believe them, others are not very strong, but they are all theories. A theory doesn't have to be called a law if it is very strong. So if your teacher says that something in science is a theory you don't need to think that this thing is "only" a theory, it could be a very good one and science is still happy to call it a theory. Scientists like to be extremely sure about things so calling something only a theory is no insult at all.

2016-05-23 07:08:18 · answer #3 · answered by ? 3 · 0 0

Dude.....u know what...........
Electricity not always flows from a negative to a positive pole..................it's a common misconception...!!!!!!
Actually current flows from a Higher Potential.....to a Lower Potential...........!!!!!!!!!
For a current flow one end of the terminal should be at a higher voltage magnitude....and other at lower.....which would create a potential diff for the current flow..!!!!!!!

When u touch only the wire on the electric pole.....yr whole body remains at only a single potential.....which is equal to that of the wire............so current doesn't flows...!!!!!
but when yr body part touches ground......that part gets the potential of the ground.....that is its potential becomes.....ZERO.......which creates the potential difference that allows the current flow.............!!!!!!!!!

Earth is not NEGATIVE.....it's actually ZERO...!!!!!!!!!
if u connect a negative pole to ground.......then also current would flow.....as zero is higher than a negative no......so there again would be a potential difference...that would cause current flow...as i said earlier...!!!!!!

2007-11-15 06:27:34 · answer #4 · answered by abc_xyz_ss 2 · 0 2

I can see that you do not fully understand the concept.Look for a book called Electricity and how it works it explains this question better than I can.

2007-11-15 06:18:01 · answer #5 · answered by the rocket 4 · 0 3

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