# Guys i have question plz :)

Discussion in 'Homework Help' started by Ats1992, Dec 11, 2009.

1. ### Ats1992 Thread Starter New Member

Dec 11, 2009
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I have an assignment and have some questions to ask and il realy appreciate the help

1:Calculation of total impedance in series and parallel circuits USING COMPLEX NUMBERS

those last 2 words made my part alot harder so plz if u can just lead me to some thread or smthn that can help me

thx alot ....

2. ### t06afre AAC Fanatic!

May 11, 2009
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You must tell us more. What do you not understand?

3. ### Papabravo Expert

Feb 24, 2006
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The algebra of complex numbers does not change the physics of series and parallel circuits.

1. In a series circuit you can add complex impedances by adding them together. To do this you add the real parts together and you add the imaginary parts together. This is just the same thing as collecting like terms in the ordinary algebra of real numbers.
2. In a parallel circuit you can use the same rule that is used for resistors. The reciprocal of the total impedance is the sum of the reciprocals of the individual branches.
3. For two parallel branches Z1 || Z2 is just (Z1)(Z2)/(Z1 + Z2)
To multiply complex numbers you use FOIL (First, outer, inner, last) which gives four terms. Then you group the real and imaginary parts together. To divide complex numbers, you multiply numerator and denominator by the complex conjugate of the denominator. This does not change the value of the complex fraction, but it does make the demoninator a real number.