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The main difference between resistance and impedance is how they react to AC and DC currents. The flow of alternate current is governed by impedance, while the flow of AC and DC current is controlled by resistance. The distinction between resistance and impedance, the type of circuit in which they work, the elements on which they depend, their notation, real and imaginary numbers, the effect of frequency on them, phase angle, power dissipation, and stored energy are all explained here.
Resistance
Resistance is produced in a conductor as a result of electron mobility generated by the material’s ionic lattice, which permits electrical power to be converted to heat. On the other hand, electrical resistance is the polar opposite of steady-state current. Whenever a DC system is used to expose a complete resistance, it varies with frequency.
Resistance with Sinusoidal Supply
Whenever the switch is in the Off position, an AC voltage (V) is supplied to the resistor (R). This voltage is capable of moving current. This current will rise and decrease as the main voltage rises and falls in a sinusoidal manner. Since the load is a resistance, the voltage and current will both reach their maximum value and then return to zero at the same time, that is, they will rise and drop at the same time, which is referred to as “in-phase.”
The frequency equation I(t), where I is the maximum current value and is the phase angle coefficient, represents the electrical current which goes through the AC resistance as it fluctuates in sinusoidal format over time. For any specified current, like the current flowing through a resistor, we can demonstrate this.
The peak voltage or maximum in R’s terminals can be computed using Ohm’s Law as follows:
As a consequence, the alternating current in the resistor fluctuates in a sinusoidal manner around the applied voltage for a given resistive system. Because the basic frequency is the same for both current and voltage, their phasors will have the same values.
In other words, if an AC resistance is provided, the voltage and current do not change phase. As a consequence, the current can reach its minimum, maximum, and zero values when the voltage reaches its minimum, maximum, and zero values in its sinusoidal diagram.
Impedance
Impedance is a word that means the characteristics of capacitance and inductance in AC electrical circuits. This statistic is also impacted by frequency. Impedance and reactance are typically used interchangeably and are often stated to as the same thing. It’s vital to understand which reactance relates to the resistance that capacitors and inductors impose on the AC diagram, while impedance refers to the sum of reactance and resistance.
Any entire main circuit instrument, including a resistor, may be mathematically described based on its current and voltage, and the voltage within a pure ohmic resistor is directly connected to the current running via it, as stated by Ohm’s Law, as we can see in the resistor instructions.
Impedance of a resistor
Resistors in AC circuits operate similarly to their equivalents in DC circuits. A resistor’s impedance consists primarily of the real component, that is equal to the resistor’s resistance. As a consequence, a resistor’s impedance can be written as:
Here Z represents impedance and R denotes resistor resistance. A resistor, by definition, has no reactance and hence cannot store energy.
Impedance of a capacitor
Capacitors are electronic components that add capacitance to a circuit. They’re employed to store electrical energy in the form of an electric field for a short period of time. Although theoretically valid, this definition means less to a hobbyist or even most engineers. In the time domain, it’s probably more accurate to say that capacitors are employed to lag the voltage by 90 degrees compared to the current.
The capacitor current is said to be 90 degrees ahead of the capacitor voltage. For the capacitor impedance, the following equation is used to express this fact using complex numbers:
where ZC is a capacitor’s impedance, ω is its angular frequency, and C is its capacitance. This formula itself exposes a number of facts:
An ideal capacitor has zero resistance.
For all frequency and capacitance values, the reactance of an ideal capacitor, and hence its impedance, is negative.
The effective impedance (absolute value) of a capacitor is proportional to its frequency, and it always drops with frequency for perfect capacitors.
Impedance of an inductor
Inductors, on the other hand, are components that add inductance to a circuit. They’re employed to store electrical energy in the form of a magnetic field for a short period of time. Inductors are used to lag the current by 90 degrees in the time domain when compared to the voltage.
An inductor’s voltage is 90 degrees forward of the capacitor current. The impedance of an inductor is calculated using the following equation:
ZL=jωL
where ZL is the inductor’s impedance, is the angular frequency, and L is the inductor’s inductance. From this formula, numerous assumptions can be drawn:
A perfect inductor has zero resistance.
For all frequency and inductance values, the reactance of an ideal inductor, and hence its impedance, is positive.
An inductor’s effective impedance (absolute value) is proportional to its frequency, and for ideal inductors, it always rises with frequency.
Things to Remember
The main difference between resistance and impedance is how they respond to AC and DC currents.
The flow of alternate current is governed by impedance, while the flow of AC and DC current is controlled by resistance.
The total opposite of steady-state current is electrical resistance. Whenever a DC system is used to reveal a complete resistance, it varies with frequency.
Impedance is a word that means the properties of capacitance and inductance in AC electrical circuits. Impedance is affected by frequency.
Whenever an AC resistance is introduced, the voltage and current do not change phase. As a consequence, the current can reach its minimum, maximum, and zero values when the voltage reaches its minimum, maximum, and zero values in its sinusoidal diagram.
Conclusion
Electron mobility generated by the material’s ionic lattice causes resistance in a conductor, allowing electrical power to be transferred to heat. The properties of capacitance and inductance in AC electrical circuits are referred to as impedance. Frequency has an impact on this statistic as well. Impedance and reactance are frequently interchanged and referred to as the same phenomenon.
