When talking about AC since the voltage changes constantly , it is often easier to use an average or mean. To accomplish that, we use a method called "Root mean squared. Home and office outlets are almost always AC. This is because generating and transporting AC across long distances is relatively easy. At high voltages over kV , less energy is lost in electrical power transmission.
Higher voltages mean lower currents, and lower currents mean less heat generated in the power line due to resistance. AC can be converted to and from high voltages easily using transformers. 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. The only difference between a generator and a motor is that a motor converts electrical energy into mechanical energy.
These motors are used in all kinds of appliances like refrigerators, washing machines, and dishwashers. If there are two mutually inductive coils and one is energized with AC, an AC voltage will be created in the other coil.
The fundamental use of a transformer is stepping voltage up or down from the powered coil to the unpowered coil. This provides AC an advantaged well above DC in the realm of power distribution because, as mentioned above, transmitting electrical power over long distances is a lot more efficient with higher, stepped-up voltages and smaller, stepped-down currents.
Before reaching power outlets, voltage is stepped back down and current is stepped back up. This type of transformer technology has made long-range electric power distribution efficient and practical. Without transformers, it would be far too costly to construct power systems in their current long-distance form. And, because mutual inductance relies on changing magnetic fields, transformers only work with AC.
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Ocean Acidification. Rising Sea Level. Alternating current Alternating current AC is the type of electric current generated by the vast majority of power plants and used by most power distribution systems. Figure 1. An animation from a PhET simulation [2] of alternating current which has been slowed down considerably.
See direct current for a comparison. Brain et al. How Electricity Works [Online]. Pigman power engineer for Tacoma Power, Sept. Direct current is popular in applications that contains batteries, are charged by plugging an AC to DC adapter into a wall, or uses a USB cable to charge. Examples of these products are flashlights, cell phones, modern day televisions these contain an adapter which converts AC power to DC power , and hybrid cars.
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