Impedance, Resistance, Reactance, Admittance, Conductance, Susceptance, and Their Types Explained
IMPEDANCE :
“Impedance is the total resistance/opposition offered by the circuit elements to the flow of alternating or direct current!”
OR
“The impedance of a circuit is the ratio of the phasor voltage (V) to the phasor current (I)”
It is denoted by Z.
Z=V/I
As a complex quantity, we can write it as:
Z=R+jX
It is a vector (two-dimensional) quantity consisting of two independent scalar (one-dimensional) phenomena: resistance and reactance!
RESISTANCE:
“Resistance of an element denotes its ability to resist the flow of electric current”
OR
“It is a measure of the extent to which a substance opposes the movement of electrons among its atoms”
It is denoted by R.
The more easily the atoms give up and/or accept electrons, the lower the resistance, which is measured in ohms.
It is observed with alternating current (AC) and also with direct current (DC).
Types of Resistance:
· HIGH RESISTANCE :
Substances with High-resistance are called insulators or dielectrics and include materials such as polyethylene, mica, and glass.
· LOW RESISTANCE:
Substances with low resistance are called electrical conductors and include materials such as copper, silver, and gold.
· INTERMEDIATE RESISTANCE:
Substances with intermediate levels of resistance are called semiconductors and include materials such as silicon, germanium, and gallium arsenide.
REACTANCE:
t is denoted by X.
It is expressed in ohms.
It is observed for AC (alternating current), but not for DC (direct current).
TYPES OF REACTANCE:
· INDUCTIVE REACTANCE:
When AC (alternating current) passes through a component that contains reactance, energy might be stored and released in the form of a magnetic field which is known as inductive reactance.
It is denoted by +jXL
· CAPACITIVE REACTANCE:
When AC (alternating current) passes through a component that contains reactance, energy might be stored and released in the form of an electric field which is known as capacitive reactance.
It is denoted by –jXC
EXPLANATION:
Reactance is conventionally multiplied by the positive square root of -1, which is the unit imaginary number called the j operator, to express Z as a complex number of the form R + jXL (when the net reactance is inductive) or R – jXC (when the net reactance is capacitive).
ADMITTANCE :
“Admittance is the allowance of circuit elements to the flow of alternating current or direct current “.
OR
“It is the inverse of impedance” It is denoted by Y.
We can write as:
Y=1/Z=I/V
As a complex quantity, we can write it as:
Y=G+jB
Admittance is a vector quantity comprised of two independent scalar phenomena: conductance and susceptance
CONDUCTANCE:
”Conductance is the ability of an element to conduct electric current.”
OR
“It is the inverse of resistance” It is denoted by G.
G=1/RThe more easily the charge carriers move in response to a given applied electric potential, the higher the conductance, which is expressed in positive real-number (Siemens) or (Mhos).
Conductance is observed with AC and also with direct current DC.
SUSCEPTANCE:
”Susceptance is an expression of the readiness with which an electronic component, circuit, or system releases stored energy as the current and voltage fluctuate”
OR
“It is a reciprocal of reactance” It is denoted by B.
B=1/XSusceptance is expressed in the imaginary number Siemens.
Susceptance is observed with AC, but not for DC.
TYPES OF SUSCEPTANCE:
- INDUCTIVE SUSCEPTANCE: When AC (alternating current) passes through a component that contains susceptance, energy might be stored and released in the form of a magnetic field which is known as inductive susceptance.
It is denoted by – jBL - CAPACITIVE SUSCEPTANCE: When AC (alternating current) passes through a component that contains susceptance, energy might be stored and released in the form of an electric field which is known as capacitive susceptance.
It is denoted by + jBC
EXPLANATION:
Admittance is the vector sum of conductance and susceptance. Susceptance is conventionally multiplied by the positive square root of -1, the unit imaginary number called symbolized by j , to express Y as a complex quantity G – jBL (when the net susceptance is inductive) or G + jBC (when the net susceptance is capacitive).
In parallel circuits, conductance and susceptance add together independently to yield the composite admittance. In series circuits, conductance and susceptance combine in a more complicated manner. In these situations, it is easier to convert conductance to resistance, susceptance to reactance, and then calculate the composite impedance.
Impedance & Admittance:
| ELEMENT | IMPEDENCEZ=V/I | ADMITTANCE = I/V |
| R | ZR= R | YR= 1/R |
| L | ZL= jwL | YL= 1/jwL |
| C | ZC= 1/jwC | YC= jwC |
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