Key Differences Between Resistance and Impedance

Introduction:
Resistance and impedance are terms that often come up in discussions of electrical circuits, but they are not the same. Understanding their differences is crucial for anyone working with electronic components, especially when dealing with alternating current (AC) and direct current (DC) circuits.

Resistance:
Resistance is a measure of the opposition to the flow of direct current (DC) in a conductor. It is a property inherent to materials that restricts the movement of electrons. The unit of measurement for resistance is the Ohm (Ω). Resistance is constant in a DC circuit, as there is no variation in current or voltage over time.

Impedance:
Impedance, on the other hand, is the opposition to alternating current (AC) and combines both resistance and reactance (the opposition caused by inductors and capacitors). Like resistance, impedance is also measured in Ohms (Ω), but it varies with the frequency of the AC signal. It is a complex quantity that includes both magnitude and phase components, depending on the reactive elements in the circuit.

Key Differences:
1. Type of Circuit:
Resistance is associated with DC circuits, while impedance is used for AC circuits.
2. Components:
Resistance is determined by the physical properties of the conductor, while impedance includes both the resistance and reactance (inductive and capacitive elements).
3. Behavior:
Resistance is constant over time, whereas impedance can change depending on the frequency of the AC signal.

Conclusion:
Resistance and impedance both measure the opposition to current, but they differ in how they apply to different types of circuits and how they behave with changing signals. Resistance is constant in DC circuits, while impedance accounts for frequency-dependent factors in AC circuits.