Introduction

Resistance and impedance are two concepts in electrical engineering that refer to the opposition to the flow of electric current in a circuit.

Resistance

Resistance is a measure of the opposition to the flow of electric current in a circuit due to the collision of electrons with the atomic structures of the conductor material. It is a scalar quantity and is represented by the symbol R. The unit of resistance is ohms (Ω). Resistance is directly proportional to the length of the conductor and inversely proportional to its cross-sectional area.

Impedance

Impedance, on the other hand, is a measure of the total opposition to the flow of alternating current (AC) in a circuit and takes into account not only resistance but also reactance. Reactance is the opposition to the flow of electric current in a circuit due to the capacitive or inductive effect of the circuit components. Impedance is a complex quantity and is represented by the symbol Z. It has both magnitude and phase, which are represented in terms of magnitude (in ohms) and phase angle (in degrees) respectively.

Conclusion

In summary, resistance is a measure of opposition to the flow of direct current (DC) due to the collision of electrons in a conductor, while impedance is a measure of the opposition to the flow of alternating current (AC) due to both resistance and reactance in a circuit.