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Current is defined as the rate at which electrons flow through a closed circuit. The SI unit of current is Ampere. A direct current is a type of current that flows in the same direction, whereas the alternating current is a type of current that changes its direction and magnitude at fixed intervals of time. The properties of AC are that it reverses its direction periodically. The graph for an AC cycle is similar to that of a sine wave. Alternating Current is more dangerous than Direct current due to its frequency.
History
The first electrical generator used to produce alternating current was a dynamo-electric generator. It was based on Michael Faraday’s principles. It was constructed by a French instrument maker Hippolyte Pixii in 1832. The first one to use AC was Guillaume Duchenne. After that, the AC was developed by the Hungarian Ganz Works company (the 1870s) and many more developments took place to form the present-day AC equipment for our use.
Properties of AC
- An alternating current is an electric current that changes its direction in specific time intervals.
- This is the main type of current used in businesses and residences.
- The waveform of the AC cycle is similar to that of a sine curve.
- AC is more dangerous than DC as AC with less frequency is more dangerous than DC having the same voltage level.
- AC voltage can be increased or decreased with the help of a transformer, and hence it is used on a large scale.
- AC at high frequency is dangerous as the current flows on the surface of the wire.
Working of an AC
It is already known that current is generated by the movement of the negatively charged electrons. In the case of alternating current, electrons also move but not a very long distance. Electrons in an AC circuit generally move back and forth in one direction for about 1/60th of a second. After that, the electron changes its direction and moves back and forth for another 1/60th second and repeats this process. This way, the direction of alternating current changes.
AC Cycle
An AC cycle is in the form of a sine wave as the AC currents keep changing their voltage. Before understanding the AC cycle, let us understand a few terms:
- Amplitude: It is the maximum value of the current of voltage, and in the graph, it is the distance between the x-axis and the highest peak. It can be negative or positive. Here, a negative peak denotes that the direction of the current is opposite.
- Cycle: The one completed repetition of the sine wave pattern produced by 1 complete revolution i.e. 360°.
- Frequency: It is the number of cycles an AC sine wave makes in a second.
The peak to peak value is twice the amplitude of a wave, and it denotes the maximum available voltage.
For example, let us consider that a wave starts from 0, reaches a maximum in the positive direction of the y axis and then curves down towards the y axis and reaches 0. From there, it bends in the opposite direction, that is the negative direction of the y axis. It again reaches to maximum and then again returns to 0. This is one complete cycle and is known as the sine wave. The AC cycle also exhibits this kind of waveform.
The frequency of AC is approximately 60 cycles per second.
Benefits of AC
- It is used to transmit information like in case of cable television, telephones, and many more objects.
- It is very easy to produce and is more reasonable.
- There is low waste energy transfer across large distances.
- AC can be easily converted to DC with the help of rectifiers.
Conclusion
Current is defined as the rate at which electrons flow through a closed circuit. The SI unit of current is Ampere. The properties of AC are that it reverses its direction periodically. The graph for an AC cycle is similar to that of a sine wave. In the sine wave, the wave starts from 0, moves in the direction of the positive y-axis, and then again turns back to 0. From there, it moves in the direction of the negative y-axis and then again comes back to 0, completing one whole cycle. The first one to use AC was Guillaume Duchenne.
