What is an Alternating Current?
Alternating current (AC) electricity is the type of electricity most commonly used in homes and businesses all over the world. It is said to “alternate” because it reverses direction in an electrical circuit at regular intervals, usually many times per second. Alternating current is created by an electric generator, which determines the frequency of these oscillations. In the United States, alternating current is generated at 60 hertz, meaning that the current alternates 60 times per second. There are a number of reasons why most electrical power plants produce AC rather than DC or direct current, where electrons flow constantly in one direction. First, large generators produce AC naturally, so conversion to DC would require an extra step and therefore an added cost. Secondly, and perhaps most importantly, electrical transformers must have alternating current to operate. Transformers are a crucial part of a power grid, because they perform the task of stepping up electrical voltage for
An alternating current (AC, also ac) is an electric current whose direction reverses cyclically, as opposed to direct current, whose direction remains constant. The usual waveform of an AC power circuit is a sine wave, as this results in the most efficient transmission of energy. However in certain applications different waveforms are used, such as triangular or square waves. Used generically, AC refers to the form in which electricity is delivered to businesses and residences. However, audio and radio signals carried on electrical wires are also examples of alternating current. In these applications, an important goal is often the recovery of information encoded (or modulated) onto the AC signal.
, the current used for the light bulb, the television and nearly all other electrical equipment that we use in our everyday live! Don’t ever touch a live plug or wire though, or you could kill yourself. In the plugs the current is oscillating with a fixed frequency (50 Hz) and this is not what happens on the sun. AC currents on the sun are more easily explained with the help of a long string. If you swing one end of the string the disturbance you generate propagates along the string as a single pulse. The important difference between the string and the solar magnetic field is that the magnetic field is not just one single string, is lots of field lines filling all of space. Therefore if one fieldline is perturbed by being shaken the effects spread to the neighbouring fieldlines. It is somewhat like dropping a stone into a puddle of water, where a circular wave spreads out from the centre of the impact. When more than one stone is dropped at the same time several waves appear and they m
