Electrical impedance is the measure of the opposition that a circuit presents to the passage of a current when a voltage is applied. In quantitative terms, it is the complex ratio of the voltage to the current in an alternating current (AC) circuit. Impedance extends the concept of resistance to AC circuits, and possesses both magnitude and phase, unlike resistance, which has only magnitude.
When a circuit is driven with direct current (DC), there is no distinction between impedance and resistance...
Studiot said:There is one more difference not so far mentioned.
Inductance comes in two flavours.
Self inductance
Mutual inductance
The contribution of inductance to impedance refers only to the former.
Impedance and resistance are both properties of circuit elements that determine the flow of current, but they have different definitions. Resistance is a measure of how much a material or component resists the flow of electrical current. On the other hand, impedance takes into account both the resistance and the reactance (ability to store energy) of a circuit element.
Yes, both impedance and resistance can be measured in ohms (Ω). However, the calculations for impedance and resistance are different, and they have different effects on the flow of current in a circuit. In simple circuits, resistance can be used to calculate current, while in more complex circuits with capacitors and inductors, impedance must be used.
Impedance affects the flow of current by limiting or opposing it. In a circuit with only resistance, the current will decrease as the resistance increases. In a circuit with both resistance and reactance (due to capacitors or inductors), the impedance will determine the total opposition to current flow. This can result in phase shifts and changes in the amplitude of the current.
Understanding the difference between impedance and resistance is crucial in designing and analyzing circuits. In more complex circuits, such as those found in electronic devices, impedance plays a significant role in determining the behavior of the circuit. Ignoring impedance can lead to incorrect calculations and potential damage to the circuit.
Impedance and resistance can be calculated using Ohm's Law, which states that the current (I) in a circuit is equal to the voltage (V) divided by the resistance (R) or impedance (Z): I = V/R or I = V/Z. To calculate impedance, you must also take into account the reactance of the circuit, which can be calculated using the capacitance (C) or inductance (L) and the frequency (f) of the circuit. The formulas for calculating impedance vary depending on the type of circuit element, such as capacitors or inductors.