Electrical Engineering ⇒ Topic : Representation of Alternating Voltages and Currents

Lalan
 
Representation of Alternating Voltages and Currents So far we have discussed that an alternating voltage or current may be represented in the form of (i) waves and (ii) equations. The waveform presents to the eye a very definite picture of what is happening at every instant. But it is difficult to draw the wave accurately. No doubt the current flowing at any instant can be determined from the equation form i = I_{m} sin cot but this equation presents no picture to the eye of what is happening in the circuit. The above difficulty has been overcome by representing sinusoidal alternating voltage or current by a line of definite length rotating in *anticlockwise direction at a constant angular velocity (ω).Such a rotating line is called a phasor. The length of the phasor is taken equal to the maximum value (on a suitable scale) of the alternating quantity and angular velocity equal to the angular velocity of the alternating quantity. As we shall see presently, this phasor (i. e. rotating line) will generate a sine wave.  
 
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