Which produces alternating current

AC is also capable of powering electric motors. Motors and generators are the exact same device, but motors convert electrical energy into mechanical energy if the shaft on a motor is spun, a voltage is generated at the terminals! This is useful for many large appliances like dishwashers, refrigerators, and so on, which run on AC.

Direct current is a bit easier to understand than alternating current. Rather than oscillating back and forth, DC provides a constant voltage or current. The tank can only push water one way: out the hose. Similar to our DC-producing battery, once the tank is empty, water no longer flows through the pipes. DC is defined as the "unidirectional" flow of current; current only flows in one direction.

Voltage and current can vary over time so long as the direction of flow does not change. To simplify things, we will assume that voltage is a constant. For example, we assume that a AA battery provides 1. What does this mean? It means that we can count on most DC sources to provide a constant voltage over time. In reality, a battery will slowly lose its charge, meaning that the voltage will drop as the battery is used. For most purposes, we can assume that the voltage is constant.

Almost all electronics projects and parts for sale on SparkFun run on DC. Examples of DC electronics include:. Almost every home and business is wired for AC. However, this was not an overnight decision. In the late s, a variety of inventions across the United States and Europe led to a full-scale battle between alternating current and direct current distribution.

Thomas Edison, on the other hand, had constructed DC power stations in the United States by A turning point in the battle came when George Westinghouse, a famous industrialist from Pittsburgh, purchased Nikola Tesla's patents for AC motors and transmission the next year.

Thomas Edison Image courtesy of biography. In the late s, DC could not be easily converted to high voltages. As a result, Edison proposed a system of small, local power plants that would power individual neighborhoods or city sections. Even though the voltage drop across the power lines was accounted for, power plants needed to be located within 1 mile of the end user. This limitation made power distribution in rural areas extremely difficult, if not impossible. With Tesla's patents, Westinghouse worked to perfect the AC distribution system.

Transformers provided an inexpensive method to step up the voltage of AC to several thousand volts and back down to usable levels. At higher voltages, the same power could be transmitted at much lower current, which meant less power lost due to resistance in the wires. As a result, large power plants could be located many miles away and service a greater number of people and buildings.

Over the next few years, Edison ran a campaign to highly discourage the use of AC in the United States, which included lobbying state legislatures and spreading disinformation about AC. Edison also directed several technicians to publicly electrocute animals with AC in an attempt to show that AC was more dangerous than DC. Direct current dc is the flow of electric charge in only one direction. It is the steady state of a constant-voltage circuit. Most well-known applications, however, use a time-varying voltage source.

Alternating current ac is the flow of electric charge that periodically reverses direction. An ac is produced by an alternating emf, which is generated in a power plant, as described in Induced Electric Fields.

If the ac source varies periodically, particularly sinusoidally, the circuit is known as an ac circuit. Examples include the commercial and residential power that serves so many of our needs.

This causes an electromotive force in opposite directions for both halves of the armature, which add together to allow a current to flow through the loop see Figure 1 [4].

The same result can be achieved with a rotating magnet around a stationary armature. This generation of current is entirely dependent on the armature or magnet rotating, and this rotation is powered by turbines, which rotate due to one of the sources of energy listed above.

For more information, visit hyperphysics. As seen in Figure 2, both of the arms of the armature are connected to slipping contacts called brushes [5]. One of the brushes is connected to a wire which connects to a power distribution system and eventually leads back to the wire connecting to the other brush, completing the circuit and allowing the generator to power devices.

As the armature rotates, the segment of the velocity of the armature perpendicular to the magnetic field changes direction. In other words, each half of the armature periodically changes direction as the armature rotates. This leads the current to experience a periodic reversal of the direction. In addition, as the magnetic force is directly proportional to the segment of the velocity of the charge that is perpendicular to the magnetic field , the electromotive force in the circuit varies as the segment of the velocity of the armature perpendicular to the field varies.

This sinusoidally varying voltage coupled with the periodically reversing current is characteristic of alternating current [4].

Cars use a type of ac generator called an alternator to keep the battery charged and to run the electrical system while the engine is working.

The diagram shows a simple alternator. As one side of the coil moves up through the magnetic field, a potential difference is induced created in one direction. As the rotation continues and that side of the coil moves down, the induced potential difference reverses direction.