When are alternating currents commonly used?

Answer 1

The electrical power that the public utility company delivers to you via the

wall outlets in your house is supplied in the form of alternating voltage,

which produces an alternating current through any device you plug into

one of the outlets.

Answer 2

When a current is alternating it is going back and forth between being positive and negative. What this means is that if you were to keep track of an individual electron making up the AC current you would find that the electron drifts back and forth in the same location. In the case of DC or Direct Current the electrons drift in the same direction continuously.

The AC current and voltage in North American homes has a frequency of 60 Hz or 60 cycles/second, which means that the electrons drifts back and forth 60 times each second. In Europe it is 50 Hz. Its variation with time is sinusoidal. (Refer to related links below).

The great advantage of using alternating current/voltage is that you can use a transformer to convert the "form" in which the power is transmitted when you need to cover long distances.

In North American homes the voltage is 120 Volts AC, but along large transmission lines the voltage is around 100 000 Volts AC. The voltage of the transmission lines along the streets is tens of thousands of Volts AC.

To understand why this is done you have to understand that power is the product of voltage times current or P=VI. For the same amount of power that is traveling along the transmission wires, because the voltage is higher the current is smaller. Because the current is smaller less energy is lost in the resistance of the wires of the transmission lines. The loss of energy due to resistance in the wires is a major obstacle. The second main advantage is that AC current/voltage allows for some very simple motor designs. The induction motor works on AC voltages and is used in almost all fans and pumps.

To learn more details go the the related links below.

Answer 3

Household current - the current that comes out of the electric outlet, usually 110V or 220V - is alternating current. The current used in industry is AC, as well. Alternating current is very convenient, mainly because its voltage can easily be changed with Transformers. This isn't the case with DC. Some end-devices - mainly electronic devices - use DC (direct current), but that's no problem, since the AC can easily be converted to DC, as well. On the other hand, the current that comes out of batteries and cells is DC.

Answer 4

Everything that isn't running on batteries is using A.C. to operate. The battery charger uses A.C. Your lighting and all things that plug into the outlets use A.C.