Difference between resistance and impedance
Resistance vs impedance:
Electricity has most undoubtedly become an integral part of our existence. And yet, there are many obstacles and issues that spring up within the circuits when it comes to the usage of electricity and resistance and impedance are two such factors which directly affect the flow of electricity in a circuit. Let us observe whether we can make a distinction between the many factors that these two aspects manifest within themselves.
What is resistance?
Resistance in an electric element can be described as the opposition to the passage of an electric current through that particular element which is measured by the SI unit of the ohm (Ω). Resistance is a concept used for Direct current also known as DC and it occurs due to electrons in a conductor colliding with its ionic lattice which ultimately results in that electrical energy being converted into heat. It acts opposite to the current or a force which ‘resists’ it and this resistivity varies from one material to another. Resistance can be calculated by using the equation below where the R stands for resistance, I stands for the current through the conductor in units of amperes and V stands for the potential difference measured across the conductor in units of volts.
What is impedance?
The term impedance was coined by Oliver Heaviside in July 1886.Impedance can be defined as the measure of the opposition that an electrical circuit applies to the passage of a current when a voltage is presented. Impedance is applied to Alternative Current circuits, which are also known as AC. Impedance is measured by Ohm units and it also includes reactance which is in turn, can be either inductive or capacitive. Reactance is thus a circuit element that opposes to an Alternating current and thereby with its help, the impedance of a certain apparels can be calculated.
What is the difference between impedance and resistance?
Resistance and impedance have different fundamental origins even though the formula that stands to calculate their value is the same which is R= I/V. However, impedance can also be indicated as a more general term for resistance that also includes reactance. If one is supplied with the reactance of a certain element, figuring out the resistance enables an individual to calculate the impedance. Thereby, resistance becomes an essential ingredient in calculating impedance whereas impedance is not needed for calculating resistance.
However, the main difference between resistance and impedance can be put down to the fact that while resistance occurs in Direct Current (DC) contexts, impedance occurs in Alternating current (AC) contexts. Another factor which differentiates the two is that while resistance will be much simpler to figure out as it only consists of non-shifting phases of voltage and current, impedance on the other hand, is said to be much more complex as it will be based upon phase shifts and reactance as well.
Because of the above mentioned fact, when taking impedance in to account, one may feel the need to observe an overall and a more detailed figure of the circuit. And yet, in the case of calculating resistance, one may not need to be provided with an overall figure of the circuit.
Impedance possesses both magnitude and phase unlike resistance which has only magnitude. Also, while both impedance and resistance are expressed by the unit ohms, mathematically however, they are denoted differently. Impedance is often denoted with symbol (Z) while resistance is often denoted by the symbol (R). Another factor that should be taken in to account when comparing these two phenomena is that one is quite capable of finding resistance everywhere. And yet, in order to come across impedance, there has to exist an AC or a fluctuating DC current. However, it is often assumed that these two words are synonymous and even simple circuits which possess absolutely no reactance are still referred with the term ‘impedance’. And yet, since impedance is more of a general term, the usage of the two words interchangeably is quite acceptable.