Well, at the most basic level, it's because that's the way it's made! An electrical generator is a huge magnetic machine which induces currents, and being circular (360 degrees), that's the "shape" the electricity comes out.
Yes Asad, you are right to an extent, sine & cosine waves are the most basic waveforms to study. It is easy to integrate, differentiate in short you can work upon such kind of wave. If you take up square wave which is also made up of sine wave & harmonics, so studying sine wave forms the basis.
It is the wave form produced in the least expensive form of a rotating armature in a constant magnetic field. Pulsating DC (simply on and off) through a transformer produces a pseudo sine wave, and a modified PWM (Pulse Wave Modulator) - stepped - produces a modified sine wave closer to a mechanically produced sine wave. A modified PWM is what most power inverters use to convert 12V DC battery to 120V AC for appliances.
It simply is how the alternating current wave form is produced in an alternator (AC generator with slip rings). The RMS (Root Mean Square) power is 0.707% of peak, or peak is 1.414% of RMS. 120VAC RMS is 169.68V AC peak @ 60 CPS/Hz.
The sine wave form is not a specifically 'targeted' wave form, it is the 'result of' mechanical rotation through a magnetic field.
Through a PWM, there can be a square wave form or stepped wave form. Since the sine wave that is naturally produced in an alternator is the most cost effective, the classic sine wave is what is most commonly used.
The main reason we use a sine wave in ac circuits is due to the behaviour of a generator which generates alternating current
If you plot voltage output from a generator according to time you will derive a graph which is sinusoidal in shape and has a direct relation with degrees and radians making up a complete circle.
Or one cycle or 360 degrees or 2 pi radians the units of angular measurement
For a better and more complete understanding of the subject refer to this link below
If. You use google or a similar search engine which takes a little practice
Can be a little challenging at times would you believe there are some more thorough explanations to this subject as well
I also suggest further studies in mathematics which if you google again, does mean a little bit of effort, You can gain more understanding by looking up the following
The vertical and horizontal projections of a rotating line
The measurement of Angles in degrees
The definition of the Six Tigonometric Functions
Graphical Representation of the properties of the function Y = Sin (pheta )
or
if you can manage to download a file please see link below
If we rotate any thing through 360 degrees, it produces sine wave against time and radius of the rotating device. Radius gives amplitude of the sine wave and time required to rotate wheel for one rotation gives frequency.
To see sine wave; just mark a point on bicycle tyre and mark the place touching the wheel on ground. Move bicycle and trace the movement of mark on tyre for one complete rotation; you will get a sine wave. Similarly when any dynamo or generator armature rotates it traces sine wave.
Thus armature coil continuously rotates in magnetic field producing EMF similar to sine wave. number of rotation per second gives frequency of sine wave in Hertz. Thus all AC voltages currents are sine waves.
AC is generated at lowest price and it is available on wall socket.
AC do not have any harmonic frequencies so it do not produce any noise in device when used.
Greetings, all explanations are good info. I just would like to add a simple bit of info for the non as well educated persons. The sine wave is a result of the rotating magnetic interaction when the magnets (which, remember, have polarity as in north and south or if you wish plus and minus)rotate past the separate coils in the generator. As the rotating magnetic field turns, both the attracting and the repelling polarity of the magnets pass the coils at opposing times. This rise and fall, or attraction and repulsion, with neutral or 0 in the center of the two that creates a sine wave as the potential rises and then falls 60 times a second in the USA and 50 times in the UK. As the magnets approach and pass then move away and the next magnet approaches and rises then passes and so on that creates the wave as voltage rises to peak and falls to 0 on to the minus peak as the magnet passes and rises back past 0 to the positive peak. Hence the name alternating current. It alternates between the positve and negative polarities in direct ratio to the magnetic field reversing polarity. (Magnet polarity- lay 2 end to end they will either attract or repel each other, flip and they will behave opposite)
The sine wave is the fundamental waveform used in AC circuits because it naturally results from the operation of electrical generators, which produce voltage by rotating an armature within a magnetic field. This rotation through 360 degrees induces a sinusoidal voltage output corresponding to the angular position of the armature. The sine wave is mathematically simple to analyze, being easy to integrate and differentiate, and it contains no harmonic frequencies, unlike other waveforms such as square waves which are composed of multiple sine wave harmonics. The root mean square (RMS) value of a sine wave relates predictably to its peak value, facilitating power calculations. Additionally, sine waves minimize electrical noise and distortion in devices. Alternative waveforms like modified sine waves or square waves can be generated via pulse width modulation (PWM) in inverters, but the pure sine wave remains the most cost-effective and naturally produced waveform in AC power systems. Summary generated by the language model.
