What is the neutral wire for in a household AC circuit?

You have some other very good answers. Now some practical advice, purchase a couple of books and read them thoroughly. You seem to have a basic DC knowledge, AC is enough different that any mistake can kill. When in doubt about higher voltage or AC systems, DON'T. Ask and ask again until you understand. The books should cover AC generation and distribution and Basic House Wiring. The generation and Distribution will take several readings to grasp what and why. Some very senior and highly qualified electricians never seem to grasp it. Some other good reference material will include transformers and motors, both single phase and multiple phase. For excellent training and a chance to earn while you learn, enroll in an IBEW Apprenticeship program.

Wrong, the tall slot is the neutral (white wire), the round is the ground (green or bare), and the small blade is the hot (most often black, the most dangerous slot is the smaller slot).

I think you may be confused by terminology, in automotive DC circuits they refer to the negative conductor as a ground, (as a representative theoretical earth connection, even though it is not actually connected to the earth), in an AC system the "Ground" is actually grounded to the earth, and it is not a circuit conductor, it is just a connection to metal parts to drain power that has leaked from the designed circuit to provide a path to operate a fusing device (which can be a circuit breaker) before it hurts anybody or causes any property damage.

The AC neutral is called neutral because it is the neutral point between the two opposite polarity hots in your service, or the center common point on a three phase system.

The short slot is the hot, it alternates pushing then pulling electricity from the neutral 60 times a second. The neutral then is the tall blade, in the NEC it is normally referred to as the "grounded conductor" rather than as a neutral except in sections were it is used in common with multiple hot wires. It is bonded to the ground at the electrical service, and so in the field it will normally read close to 0 volts.

Since it reads close to 0v you normally wont be shocked by it, but be careful, if you open a receptacle junction box and you find multiple white wires entering the junction box, if you seperate the white wires some of those wires can shock you! Not the one white that leads back to the panel, but the white wires that come from other receptacles may conduct current from a hot, through any device or light that is connected, then trying to find a path back to the panel through the whites you have disconnected.

Additional response: I think the confusion is the automotive DC term "ground" and the AC term for ground are different things. A car isn't grounded, in a car the DC term "ground" for the chassis connection should more accurately described as the "negative conductor bus", they view the isolated environment of a single vehicle and consider it equivalent to a planet, and then interchange the word ground for planet..

In AC systems the actual ground is not part of the normal current path and the ground prong is attached to the ground through the panel and ground rods. Part of the generating system also gets connected to earth, then all intermediate equipment is connected to the ground to give a current path through the moisture in the ground for leaking current back to the source. The metal parts of electrical appliances get connected to ground prong so that if current leaks to the metal parts then there is a current path back to the utility source to operate the overcurrent protection so that deadly current doesn't pass though equipment users.

In the older system before the 3-wire grounded outlet become commonplace, there were only two wires. One black (hot) and the other white (ground). This was ample since early users only had light bulbs, fan, motor, radio, or perhaps a milking machine. One side (white) was kept at ground level by hooking to a cold water pipe or rod driven into the ground so when the power distribution system was hit with lightning or (currents were induced into the system via static induction) a path to ground was always available. If both sides of the line were above ground, static discharge on one or both wires may jump through the wall and hit nearby objects looking for a path to ground. In a modern system, a third wire (usually a bare wire within the cable) was introduced to provide a chassis ground. With a chassis ground connected via the round prong of an outlet, the frames all 3-wire appliances are held at ground level. So for example, if you touch your washing machine and dryer at the same time, both boxes are held at ground level so you don't get a shock by any induced currents or leakage currents from the motor or heating elements. Both the white wire and bare wire within the cable are joined together inside the circuit breaker box on the ground bus. The ground buss is then connected via a heavy copper ground wire to the cold water pipe or ground rod. Bottom line then is that you have Black (hot), White (ground), and Bare (ground). Often the white wire is called "neutral". The black & white carry the load while the bare ground bleeds off any induction currents. Use of a 3-wire system is also necessary for spike protectors to be functional.

The terminal identification for a 120 volt, grounded outlet is that the black (hot) wire goes to the small socket on the right, neutral (white) wire goes to the larger socket on the right, and ground (bare copper) goes to the circular connector at the bottom/top.

You always need two wires to complete an electrical circuit. In a DC circuit, typically the red wire is hot, or positive (12 volts), and the black wire is ground or negative (0 volts). In a DC circuit, current flows in one direction only.

In residential wiring, hot is black, and neutral is return (not ground). Ground is ground. Residential systems operate on 120 volts AC, 60 Hz (Hertz). This means that in your home, current flow changes direction 60 times per second. There are advantages to AC that I won't get into right now.

If you follow your electrical service drop (power wires) outside your home, unless they are buried underground, you can trace them to a gray can mounted to a utility pole. That's the step-down transformer. It produces the two hot lines that go into your house (black cables) and the neutral (bare metal cable). Neutral is grounded at the transformer utility pole.

Hot and neutral are the two wires that are used by your home electrical devices. Ground is a safety conductor which is derived from eight foot roods stuck into. . .you guessed it, the ground at your house.

Just as the red wire in an automotive system carries 12 volts DC, the black wire in a home carries 120 volts AC. You can't get shocked from a properly functioning neutral (white) wire. Ground is connected to any metal you might come in contact with, on your electrical device. Ground is for safety only.

Before you touch any part of your home's electrical system, I strongly recommend you get familiar with basic residential electrical systems: what they are and how they work.

You never assume anything when dealing with electricity. The wiring is " supposed " to be hot wire to the small slot, neutral to the large slot, ground to the round plug. And yes a neutral can shock you if the circuit is complete and live. All it takes is one mistake to end your life when messing about with electricity.

I've heard that it works but when we tried it 50 years ago it did not work. We had better results using water and a cover over the wet area. Also a flashlight at night on a lawn r freshly watered area like a golf course got us many more than the electrical trick. Also if you do that with with a hot and neutral without an isolation transformer you will trip the gfi every time.

Lets see the neutral wire is actually the wire to complete the circuit. If I disconnected the wires with out turning the breaker I would disconnect the hot wire first.