Before knowing the difference between resistance and impedance, we should know that impedance is a concept related to AC whereas resistance is a concept related to DC. Their calculation of value is same which is R=V/I.
Difference Between Resistance and Impedance
Resistance is caused due to the electrons in a conductor colliding with the ionic lattice of the conductor which results in the conversion of electrical energy in heat. It could be said that electrical resistance is the opposition to steady electric current. An ideal resistance does change with frequency when connected with DC.
Impedance is the measure of the nature of opposition of the AC electricity which is created due to inductance and capacitance. This opposition varies with the frequency. Very often, reactance and impedance are thought to be the same and are interchangeably used. It is important to understand that reactance is the resistance offered to the AC current by inductors and capacitors only while impedance is the sum of the resistance and reactance. In the table below, important differences between resistance and impedance are given.
Difference Between Resistance and Impedance 


Resistance 
Impedance 
It is used in DC circuits 
It is used in AC circuits 
Resistance can be seen in both AC and DC circuits 
Impedance can be seen only in AC circuits 
It happens due to resistive elements 
It happens due to reactance and resistance 
It is represented by letter R 
It is represented by letter Z 
It is represented using real numbers such as 5.3 ohms 
It is represented using real and imaginary values such as R + ik 
It does not vary depending upon the frequency of DC current 
It varies according to the frequency of AC current. 
It does not have a magnitude and phase angle 
It does have a phase angle and magnitude 
If kept in a electromagnetic field, it only shows the power dissipation 
If kept in a electromagnetic field, it shows power dissipation and energy stored 
These were some difference between Resistance and Impedance. If you wish to find out more, download BYJU’S The Learning App.
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