In this article, we will discuss all the significant differences between resistance and impedance, i.e. resistance vs impedance.
What is Resistance?
The measure of opposition offered by a material in the flow
of electric current is called resistance.
Resistance is denoted by the letter R, and its SI unit is Ohm (Ω).
Resistance is also known as electrical friction because it results in the production of heat
when current flows through the material. The circuit element that is used to
model resistance in an electric circuit is called a resistor. Resistance is one of the fundamental parameters in every
electrical and electronic circuit.
Resistance of a conductor is given by,
Where ρ
is the resistivity or specific resistance of the material, l is the length of the conductor, and a is the area of the crosssection.
Resistance of an electric circuit equally
opposes the direct as well as alternating current.
What is Impedance?
The total opposition offered by circuit
elements of an electric circuit in the flow of alternating current is called impedance. Therefore, the term “impedance” only specifies the total opposition in an AC circuit.
Impedance is denoted by the letter Z and
it is measured in Ohm (Ω).
Impedance is a complex quantity as it has two components namely, real and
imaginary. The real part represents the resistance of an AC circuit, and the
imaginary part represents the reactance of the AC circuit.
Therefore, the impedance of an AC electric circuit is given by,
`\Z=R+jX`
Where R is the resistance of the circuit
and X is the reactance of the circuit.
After getting an overview of resistance
and impedance, let us now discuss their differences.
Difference between Resistance and Impedance
The following table gives the important differences
between resistance and impedance:
Basis of comparison 
Resistance 
Impedance 
Basic Definition 
The property of a material that restricts the flow of electric
current through it is called resistance. 
The total opposition offered by different circuit elements in
the flow of alternating current (AC) is called impedance. 
Denotation 
Resistance is denoted by the letter R. 
Impedance is denoted by the letter Z. 
Type of circuit 
Resistance is applicable in both DC and AC circuits. 
Impedance is significant in AC circuits only. 
Type of quantity 
Resistance is a real quantity. Hence, it has magnitude only. 
Impedance is a complex quantity. Hence, it has both magnitude
and phase. 
Circuit components 
The circuit component used to implement resistance in a
circuit is a resistor. 
The impedance is offered by a combination of circuit components,
such as resistors, inductors, and capacitors. 
Frequency dependence 
The resistance of an electric circuit is independent of the supply
frequency. 
The impendence of an electric circuit is the function of
frequency. 
Phase shift between I and V 
In the case of resistance, there is no phase difference
between voltage and current, i.e. phase difference is zero. 
In the case of impedance, there is a certain phase difference between
voltage and current that depends upon the value of the reactive component. 
Power factor 
In the case of resistance, the power factor is always unity. 
Impedance can cause a unity, leading, or lagging power factor
depending on the value of real and imaginary components. 
Addition 
We can add two or more resistances arithmetically. 
Two or more impedances cannot be added arithmetically, instead, they are added as per phasor algebra. 
Resistance always consumes power. This is called active power. 
Impedance consumes as well as stores power. In the case of
impedance, three types of powers are active power, reactive power, and
apparent power. 

Applications 
Resistance is used to control the flow of electric current in
a DC or AC circuit. 
Impedance is used to control the flow of current in an AC
circuit. 
Conclusion
In conclusion, this is all about the
important differences between resistance and impedance. In the above table, we
discussed all the significant differences between resistance and impedance.
However, both resistance and impedance are the measures of opposition in the
flow of electric current in electric circuits.