Name: ac circuit response: impedance and admittance
Uploaded: 2024-04-11T12:48:49.000Z
Duration: 1 min 23 s
Channel: JoVE

In AC circuits, the passive elements - the resistor, the inductor, and the capacitor - are characterized by the phasor voltage and current.
Impedance is the ratio of the phasor voltage to the current and represents the resistance to the sinusoidal current flow in an AC circuit.
For DC sources with zero frequency, the inductor operates like a short circuit with zero impedance, while the capacitor functions as an open circuit with infinite impedance.
However, at high frequencies, the inductor acts as an open circuit, and the capacitor becomes a short circuit.
Impedance is a complex quantity that can be expressed in rectangular form, where the real part denotes the resistance and the imaginary part represents the reactance.
Reactance can be positive or negative. A positive reactance implies inductive impedance, where the current lags behind the voltage. Conversely, a negative reactance signifies capacitive impedance, where the current leads the voltage.
In polar form, impedance can be characterized by its magnitude and phase angle.
Admittance, the reciprocal of impedance, can also be expressed in rectangular form, where the real and imaginary components represent the conductance and the susceptance, respectively.

impedances and admittance

Impedances and Admittance

In the realm of AC circuits, passive circuit elements like resistors, inductors, and capacitors take on a different character when characterized by phasor voltage and current. Their behavior is expressed through impedance, a vital concept in AC circuit analysis.
Impedance is a measure of resistance to sinusoidal current flow in an AC circuit. Unlike their behavior in DC circuits, where inductors appear as short circuits and capacitors as open circuits, the behavior of these components in AC circuits is frequency-dependent. At high frequencies, inductors act as open circuits, while capacitors become short circuits.
Impedance is a complex quantity with a real part denoting resistance and an imaginary part representing reactance. Reactance can be either positive or negative, indicating inductive impedance when current lags behind voltage and capacitive impedance when current leads voltage. Impedance can also be represented in polar form, highlighting its magnitude and phase angle.
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The reciprocal of impedance is admittance, which is measured in Siemens (S). Admittance represents the ease with which current flows through a circuit. It comprises conductance (real part) and susceptance (imaginary part). Admittance, like impedance, is a valuable tool in AC circuit analysis, enabling engineers to understand and manipulate electrical circuits operating under sinusoidal conditions.

In AC circuits, the passive elements - the resistor, the inductor, and the capacitor - are characterized by the phasor voltage and current.
Impedance is ...

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JoVE Core

Electrical Engineering

Unit 1

AC Circuit Analysis

KEY TERMS AND CONCEPTS

ac circuit response: impedance and admittance

AC circuit response changes with frequency, and impedance describes how resistors, inductors, and capacitors affect sinusoidal current flow. In phasor form, voltage and current are used to show this behavior in a clear way. Impedance is a key idea in AC circuit analysis because it measures opposition to current in an alternating circuit.

These components behave differently in AC than in DC. In DC circuits, inductors act like short circuits and capacitors act like open circuits. In AC circuits, their behavior depends on frequency. At high frequencies, inductors act like open circuits, while capacitors become short circuits.

Impedance is a complex quantity. Its real part is resistance, and its imaginary part is reactance. Reactance can be positive or negative. Positive reactance shows inductive impedance, where current lags behind voltage. Negative reactance shows capacitive impedance, where current leads voltage.

Impedance can also be written in polar form. This form shows both magnitude and phase angle. The reciprocal of impedance is admittance, which is measured in Siemens, or S. Admittance shows how easily current flows through a circuit.

Admittance also has two parts. Its real part is conductance, and its imaginary part is susceptance. Like impedance, admittance helps engineers analyze AC circuits under sinusoidal conditions. It gives another useful way to study and shape circuit behavior.

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Learn how impedance and admittance describe AC circuit behavior in resistors, inductors, and capacitors, including reactance, phase, and frequency effects.

AC Circuit Response: Impedance and Admittance | JoVE K12

JoVE Core Electrical Engineering offers easy-to-understand animated videos that cover fundamental concepts of electric circuits along with circuit analysis techniques. It incorporates first-order and second-order circuits using operational amplifiers and circuit transformation concepts. The inclusion of practical design examples and real-world applications through scientist-in-action videos adds significant educational value, making complex concepts accessible.

electrical engineering

AC Circuit Response: Impedance and Admittance

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