Difference Between Resistance and Impedance

The Difference Between Resistance and Impedance is explained below keeping in mind the various factors like the basic definition of resistance and impedance, a type of circuit they work in, elements on which they depends, their symbolic representation, real and imaginary numbers, the effect of frequency on them, phase angle, power dissipation and energy stored.

Difference Between Resistance and Impedance are given below in the tabulated form.

BASISRESISTANCEIMPEDANCE
DefinitionThe opposition offered to the flow of current in an electric circuit is known as the Resistance.The opposition offered to the flow of current in an AC circuit because of resistance, capacitance and inductance is known as Impedance.
CircuitResistance occurs in both AC and DC circuit.Impedance occurs only in an AC circuit.
ElementsIt is the contribution of the resistive element in the circuit.It is the contribution of both resistance and reactance.
SymbolIt is denoted by RIt is denoted by Z
Real and Imaginary ValueResistance is a simple value consisting of only real numbers. Eg: 3.4 ohms, 6.2 ohms etc.Impedance is a complex value consisting of real and imaginary values. Eg: R+ij
FrequencyResistance is constant in a circuit and does not vary according to the frequency of AC or DC.Impedance varies according to the frequency of AC current.
Phase angleResistance does not have any phase angle.Impedance have magnitude and phase angle.
Power Dissipation & energy storedIt only represents power dissipation in any material if kept in an electromagnetic field.If kept in an electromagnetic field it represents both power dissipation and energy stored.

Resistance is simply defined as the opposition to the flow of electric current in the circuit.

Impedance is opposition to the flow of AC current because of any three components that is resistive, inductive or capacitive. It is a combination of both resistance and reactance in a circuit.

The various Difference Between Resistance and Impedance are described below in detail.

  • The opposition offered to the flow of current in an electric circuit whether AC or DC is known as the Resistance. The opposition offered to the flow of current in an AC circuit because of resistance, capacitance and inductance is known as Impedance.
  • Resistance occurs in both AC and DC circuit, whereas Impedance takes place only in an AC circuit.
  • Resistance is the contribution of the resistive element in the circuit, whereas the contribution of both resistance and reactance forms Impedance.
  • Resistance is  denoted by (R) whereas impedance by (Z).
  • Resistance is a simple value consisting of only real numbers. Example: 3.4 ohms, 6.2 ohms etc. Impedance comprise of both real and imaginary numbers. Example: R+ij, where R is a real number and ij is imaginary part.
  • The Resistance of the circuit does not vary according to the frequency of AC or DC, whereas Impedance varies with the change in frequency.
  • Impedance have both magnitude and phase angle, whereas Resistance does not have phase angle.
  • Resistance if kept in an electromagnetic field represents power dissipation in any material. Similarly, if Impedance is subjected to magnetic field it represents both power dissipation and energy storage.

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