Alternating Current And Its Applications

Alternating current or alternating voltage is the current or voltage that changes its amplitude in a waveform through a conductor or medium as it flows.  It is the flow of electric current or voltage that reverses its direction in each alternation. Alternating current is abbreviated as AC. The flow of  charge reverses its direction in a circuit back and forth creating an alternating current. The magnitude of an alternating current increases from zero to a maximum for a moment and then returns back to zero.

Photo credit: library.thinkquest.org 

AC Waveform

The usual waveform of an AC circuit is a sine wave. In other applications different waveforms are used such as the triangular or square waveforms. The direction of an AC alternates between both directions either positive or negative. The AC voltage changes its waveform from zero to positive and then to zero, zero to negative and then to zero. The rate of alternation of the alternating current is cycles per second. The frequency of an AC voltage or AC current is the number of cycles per second. The frequency of an AC is measured in hertz or Hz in short. The cycles of direction change is usually about 50 to 60 cycles per second, that occurs continuously. The time taken by the AC current or voltage to complete once cycle is known as its time period.

F "Frequency in Hertz" = 1 / T "Time in Seconds"

Photo credit: pcguide.com 

Sources of AC

Alternating current is produced by alternators, generators, dynamos, oscillators, signal generators, etc.

Uses of AC

Alternating current is the type of electricity used in domestic and business houses. The cycles of direction change is usually dependent upon the type of electrical system of the place. The AC is used in our houses for lighting and heating purposes. The devices that run on AC are lighting devices, electric fans, coolers, air conditioners, electric iron, electric oven, washing machines etc.

Advantages of AC

1. Alternating current or AC can be changed from one voltage to another of the same frequency. The varying current and voltage induces a varying magnetic field in a transformer, which in terms transforms it into another voltage.

2. AC generators and motors are very simpler in design and manufacture than DC generators and motors.

Photo credit: teachersdomain.org

AC Applications

AC allows the transmission of electricity  through long distances from where it is generated to where it is  consumed. Very high AC voltage in the range of several 1000s of volts  are used for carrying energy from the power house to the substation. From the substation the high voltage is transformed into lower voltage which is supplied for the domestic purposes.

Signal waveform transformation and transmission is possible only through AC. Signals such as audio, radio etc. are carried by alternating currents of those signal frequencies.

AC transformers are used for converting higher voltage AC to lower volt AC and vice versa. It also couples similar voltage AC from one circuit to another for matching and coupling.

AC motors are used in fans, compressors, starter motors, water pumps, electric vehicles, electricity operated flights, etc. for their respective functions.

Alternating current can pass through inductance and capacitance and produce capacitive reactance and inductive reactance used for signal tuning and transformation.