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
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 .