+2 votes
91 views
What is sine wave ? How does that differ from cos waves or other waves ? What is its importance ?
asked Oct 28, 2015 in Electro-Communication by ppk | 91 views

1 Answer

+4 votes
Selected Ans.

Sine, in mathematics, is a trigonometric function of an angle.

Sine theta = Opposite side / Hypotenus.

The sine wave or sinusoid is a mathematical curve that describes a smooth repetitive oscillation. It is named after the function sine.

Any oscillation, such as a sound wave or alternating current, whose waveform is that of a sine curve.

Sine wave Relation to a circle : 

https://en.wikipedia.org/wiki/Sine#/media/File:Circle_cos_sin.gif


Importance of Sine Wave :

  • Sine waves are so important and so studied because the sine wave is the most basic and the most common waveform for AC Signal variations.
  • A rotary generator is a very important device that allows us to have electricity in our homes. Most electricity is made by turbine blades rotating at speeds high enough to produce electricity in a generator. 
  • The waveform produced by this generator is a sine wave, whose output is proportional to the angle of rotation. So this means the electricity coming out of the power sockets in our houses are sine waves. 
  • Sine waves are also produced naturally in oscillator circuits, which are circuits that have an inductor and a capacitor. 
  • If you place a capacitor and inductor in a circuit in the correct orientation, the circuit will produce a sine wave in proportion to the amount of inductance and capacitance in the circuit. 
  • Thus, sine waves are produced naturally in many circuits and devices and very important, so that's why they are so studied

Pure Sine wave :

The output voltage of a sine-wave inverter has a sine wave-form like the sine wave-form of the mains / utility voltage. In a sine wave, the voltage rises and falls smoothly with a smoothly changing phase angle and also changes its polarity instantly when it crosses 0 Volts. 

In a modified sine wave, the voltage rises and falls abruptly, the phase angle also changes abruptly and it sits at 0 Volts for some time before changing its polarity. 

Below fig shows pure and modified sine waves:

Sine Vs Cosine waves :

A cosine wave is a signal waveform with a shape identical to that of a sine wave , except each point on the cosine wave occurs exactly 1/4 cycle earlier than the corresponding point on the sine wave.

References :

http://www.allaboutcircuits.com/textbook/alternating-current/chpt-1/ac-waveforms/
https://en.wikipedia.org/wiki/Sine_wave
http://www.learningaboutelectronics.com/Articles/Why-are-sine-waves-so-used-and-important
http://www.samlexamerica.com/support/faqs/faq02.aspx
http://whatis.techtarget.com/definition/cosine-wave

answered Oct 30, 2015 by slow_learner
selected Nov 11, 2015 by ppk