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resistance is real, the other purely imaginary. AnswerResistance is the opposition to the flow of current (AC or DC) which is proportional to a conductor's cross-section…al area and resistivity, and inversely proportional to its length. Reactance is the opposition to AC current due to either the circuit's inductance or its capacitance, and are termed inductive reactance and capacitive reactance. Resistance and reactance are both measured in ohms.Inductive reactance is proportional to the circuit's inductance and the frequency of the supply; capacitive reactance is inversely proportional to the circuit's capacitance and the frequency of its supply. In other words, inductive reactance increases with frequency, whereas capacitive reactance decreases with frequency.All AC circuits contain resistance, and most contain some degree of inductance and/or capacitance. So the opposition offered by a circuit to AC current includes resistance together with some combination of inductive and/or capacitive reactance.It's incorrect to suggest that reactance is 'imaginary' in the every day sense of the word -it exists, so it must be 'real'. In this context, 'imaginary' is a mathematical term that indicates that if resistance and reactance were represented in a vector diagram (called an 'impedence diagram'), then reactance quantity would lie at right-angles to the resistance quantity. For this reason, the overall opposition to current flow, which is called impedance, is not the algebraic sum of resistance and reactance, but the vector sum of the two. So, for example, if a circuit had a resistance of, say, 4 ohms, and its inductive reactance was 3 ohms, then its impedance would be 5 ohms -not 7 ohms.Although we can represent resistance and reactance using a vector diagram (impedance diagram), strictly-speaking the quantities themselves are not vector quantities. The impedance diagram is created as a result of a phasor (vector) diagram representing the current and voltage relationships in the AC circuit. (MORE)

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