# Phasor Diagram

#### tinhnho

Joined Aug 31, 2004
34
hi everyone

Given V1 = -.41800 - .51918j and V2 = -0.27126 - .35264j
The question is: " Does V1 lead or lag V2 ? "
The answer in the book is : Delta_phi = -1.27 degree -- if possitive V1 leads

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My question is how do i know that V1 lead or lag V2 ?

Thanks everyone

#### vineethbs

Joined Nov 14, 2004
56
Originally posted by tinhnho@Nov 17 2004, 08:36 AM
hi everyone
Given V1 = -.41800 - .51918j and V2 = -0.27126 - .35264j
The question is: " Does V1 lead or lag V2 ? "
The answer in the book is : Delta_phi = -1.27 degree -- if possitive V1 leads

------------

My question is how do i know that V1 lead or lag V2 ?

Thanks everyone
[post=3605]Quoted post[/post]​
well,first of all V1 and V2 wud be the phasor representations of sinusoidal signals
in order to find which one leads or lags the other one , u have to find the phase angle between them . Consider the time t=0 for analysis .

now for both v1 and v2 the real and imag parts are -ive ,so they lie in the third quadrant.
phase angle of v1 is 180 + arctan(.51918/.41800) = 231.16 deg
phase angle of v2 is 180 + arctan(.35264/.27126) = 232.43 deg

now the phase difference is 1.27 deg

abt the answer in the book :
Now the phasor difference shows that V2 leads V1 by 1.27 deg

now as i said before , the phasors aren't fully given , so we don't know whether it is
v1(or v2) x e^(jwt) or v1 (or v2) x e^(-jwt)

now if we are taking postive freq or anticlockwise direction of rotation then v2 leads v1 else v1 leads v2 .