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Difference Between Resistance And Impedance

September 22, 2022
written by Adeel Abbas

The difference between resistance and impedance is that resistance is always positive while impedance can be either positive or negative.

Resistance and impedance are two terms that are often confused. Resistance is defined as the opposition to the flow of electrons or electric current. In electrical engineering, resistance is measured in ohms (Ω). The opposition to alternating current is presented by the combined effect of resistance and reactance in the circuit known as the impedance.

What is Resistance?

In physics, resistance refers to the tendency of a substance to oppose the passage of electricity. In electrical engineering, resistors are devices that have a high resistance to the flow of electricity. Resistors are used to limit the amount of current flowing through them. Resistance can be found by ohm law. Resistance is represented by R.


What is Impedance?

Impedance differs from resistance in that it has both magnitude and phase, unlike resistance which only has magnitude. The combination of resistance and reactance is impedance. Anything and everything that obstructs the flow of electrons within an electrical circuit is what it is.

It has an effect on the generation of current through the electrical circuit. It’s present in all of the possible components of the circuit. Impedance is symbolized by the letter Z and has a unit that is ohms. Resistance and reactance are combined into a superset.

Difference Between Resistance And Impedance

There is some difference between resistance and impedance.

Resistance is the opposition to the flow of electric current.Impedance is the combined effect of resistance and reactance.
Resistance is represented by R.Impedance is represented by Z.
R=V/I, where v is voltage and I is current.Z=R+XL, where R is resistance and XL is the reactance of the inductor.
Resistance does not have a phase angle.Impedance has a phase angle.
Resistance occurs in both AC and DC circuits.Impedance occurs in the AC circuit.

Related FAQs

Are impedance and resistance the same?

It could be said that electrical resistance is the biggest challenge to steady electric current. The impedance is the measure of the nature of opposition of the AC electricity which is created due to inductance and capacitance.

What is the main difference between resistance and impedance?

Inductive reactance increases with frequency and inductance. Capacitive reactance decreases with frequency and capacitance. Impedance represents total opposition provided by reactance and resistance.

How do you convert impedance to resistance?

In both cases, the V-I relationship is always linear in pure resistance. The symbol Z is generally used to mean resistance when using resistors in AC circuits. It is possible to say that for a Resistor, DC resistance is AC impedance, or R is Z.