Impedance vs. Reactance

Attribute	Impedance	Reactance
Definition	The total opposition to the flow of alternating current in a circuit	The opposition to the flow of alternating current due to capacitance or inductance
Symbol	Z	X
Unit	Ohms (Ω)	Ohms (Ω)
Types	Can be resistive, inductive, or capacitive	Can be inductive or capacitive
Phase Relationship	Can be in-phase or out-of-phase with voltage	90 degrees out-of-phase with voltage

Definition

Impedance and reactance are two important concepts in the field of electrical engineering. Impedance is the total opposition that a circuit presents to the flow of alternating current. It is a complex quantity that includes both resistance and reactance. Reactance, on the other hand, is the opposition to the flow of alternating current caused by capacitance or inductance in a circuit. It is a measure of the ability of a circuit element to store and release energy in the form of a magnetic or electric field.

Units

Impedance is measured in ohms, just like resistance. It is a scalar quantity that represents the total opposition to the flow of current in a circuit. Reactance, on the other hand, is also measured in ohms but is a complex quantity that can be either positive or negative. Positive reactance indicates inductive reactance, while negative reactance indicates capacitive reactance.

Types

There are two types of reactance: inductive reactance and capacitive reactance. Inductive reactance is caused by the presence of inductors in a circuit and is directly proportional to the frequency of the alternating current. Capacitive reactance, on the other hand, is caused by the presence of capacitors in a circuit and is inversely proportional to the frequency of the alternating current. Impedance, on the other hand, is the combination of resistance and reactance in a circuit.

Calculation

Impedance can be calculated using the formula Z = R + jX, where Z is the impedance, R is the resistance, and X is the reactance. Reactance, on the other hand, can be calculated using the formulas Xl = 2πfL for inductive reactance and Xc = 1/2πfC for capacitive reactance, where f is the frequency, L is the inductance, and C is the capacitance.

Effects

Impedance affects the flow of current in a circuit by limiting the amount of current that can pass through. A higher impedance means less current can flow, while a lower impedance means more current can flow. Reactance, on the other hand, affects the phase relationship between voltage and current in a circuit. Inductive reactance causes the current to lag behind the voltage, while capacitive reactance causes the current to lead the voltage.

Applications

Impedance is used in various applications in electrical engineering, such as in designing filters, matching circuits, and transmission lines. Reactance, on the other hand, is used in designing circuits that require phase shifting, such as in power factor correction and impedance matching. Both impedance and reactance play crucial roles in the design and analysis of electrical circuits.