Difference Between Impedance vs Resistance

Difference Between Impedance vs Resistance

Ever since Alessandro Volta invented the first electric circuit in 1800, technology has not been the same. This invention has been applied in diverse ways, including its use in electrical appliances such as calculators, washing machines, refrigerators, air conditioners, and so on.

If you wish to understand how these electronic devices work, then you need to familiarize yourself with associated terminologies, their meanings, and how they differ from one another.

Speaking of which, this post is going to be about the difference between resistance and impedance. These terms are similar in the sense that they both offer a level of opposition in an electric circuit.

Definition of Impedance

Impedance is the opposition in the flow of current in an alternating circuit based on resistance, capacitance, and induction. Before we go ahead to describe this “opposition” in detail, we need to point out that impedance is directly related to resistance. A lot of unseen real-time processes take place in the production of electric energy as the opposition of AC.

From another perspective, this concept can also be defined as the rate of obstruction that takes place in an AC circuit. It is a vector quantity, which means it is two-dimensional, consisting of two independent one-dimensional quantities. This phenomenon is represented by the letter Z, and real and imaginary values such as R+ik.

One difference between impedance and resistance is that they take place in different circuits. The latter is seen in DC circuits while the former is seen in AC circuits.

Definition of Resistance

Resistance is defined as an obstruction that hinders the flow of current in a direct or alternating circuit. In other words, it discourages the flow of electrons in a particular direction, which in turn, hinders the flow of electricity. Unlike in the former case which is only obtainable in AC, this concept is obtainable both in AC and DC circuits. Note that this concept is denoted by the letter “R.”

Let us use the water tank analogy to further explain this concept. Note that the water tank represents a circuit. When you have a tank filled with water with an open pipe leading down from it, the pressure caused by the height of the water causes it to rush out from the pipe.

The flow of water is comparable to current, the height of the water is comparable to the voltage, and the restriction caused by the pipe is comparable to resistance. If you add a tap the pipe, it further restricts it when it is shut, and that can be compared to an increase in resistance. When there an increase R, it reduces the flow of electrons in a particular direction.

This phenomenon may not sound feasible to a layman because, why would you want to reduce the flow of current when you need it to generate power? The fact is, without this obstruction, the circuit may likely get overloaded and this can wreck the electrical instrument. It also helps to increase battery life because less current is drawn from it.

Main Differences Between Impedance vs Resistance

Not that we are done with the introduction, let us take a look at the difference you see in resistance vs impedance comparison.

Basis of ComparisonImpedanceResistance
DefinitionThe opposition in the flow of current in an alternating circuit based on resistance, capacitance, and inductionAn obstruction that hinders the flow of current in a direct or alternating circuit
Type of circuitAlternating circuitBoth alternating and direct circuit
Letter representationZR
VariationVaries according to the frequency of ACDoes not vary
Phase angle and magnitudeIt has a phase angle and magnitudeIt does not have a magnitude or phase angle

Difference Between Impedance and Resistance: Conclusion

One thing you must keep in mind in the impedance vs resistance comparison is that these two concepts are a little hard to decipher because they are not visible to sight. Scientists could only measure these quantities by subjecting them to tests that can detect them.