AC

(noun)

Alternating current.

Related Terms

Examples of AC in the following topics:

  • Resistors in AC Circuits

    • Ohm's law applies to AC circuits as well as to DC circuits.
    • Therefore, with an AC voltage given by:
    • (b) A graph of voltage and current versus time for 60-Hz AC power.
    • The frequencies and peak voltages of AC sources differ greatly.
    • Apply Ohm's law to determine current and voltage in an AC circuit

  • Inductors in AC Circuits: Inductive Reactive and Phasor Diagrams

    • In an AC circuit with an inductor, the voltage across an inductor "leads" the current because of the Lenz' law.
    • Suppose an inductor is connected directly to an AC voltage source, as shown in .
    • This is considered an effective resistance of the inductor to AC.
    • (a) An AC voltage source in series with an inductor having negligible resistance.
    • Explain why the voltage across an inductor "leads" the current in an AC circuit with an inductor

  • Root Mean Square Values

    • Recall that most residential and commercial power sources use AC.
    • For example, Ohm's Law for AC is written as follows:
    • AC power as a function of time.
    • (b) A graph of voltage and current versus time for 60-Hz AC power.
    • The frequencies and peak voltages of AC sources differ greatly.

  • Capacitors in AC Circuits: Capacitive Reactance and Phasor Diagrams

    • In the previous Atom on "Resistors in AC Circuits", we introduced an AC power source and studied how resistors behave in AC circuits.
    • There, we used the Ohm's law (V=IR) to derive the relationship between voltage and current in AC circuits.
    • If the AC supply is connected to a resistor, then the current and voltage will be proportional to each other.
    • Since an AC voltage is applied, there is an rms current, but it is limited by the capacitor.
    • This is considered to be an effective resistance of the capacitor to AC, and so the rms current Irms in the circuit containing only a capacitor C is given by another version of Ohm's law to be $I_{rms} = \frac{V_{rms}}{X_C}$, where Vrms is the rms voltage.

  • Phase Angle and Power Factor

    • In a series RC circuit connected to an AC voltage source, voltage and current maintain a phase difference.
    • Impedance is an AC (alternating current) analogue to resistance in a DC circuit.
    • In a series RC circuit connected to an AC voltage source as shown in , conservation of charge requires current be the same in each part of the circuit at all times.
    • where $\omega$ is the angular frequency of the AC voltage source and j is the imaginary unit; j2=-1.
    • Compare the currents in the resistor and capacitor in a series RC circuit connected to an AC voltage source

  • Power

    • Power delivered to an RLC series AC circuit is dissipated by the resistance in the circuit, and is given as $P_{avg} = I_{rms} V_{rms} cos\phi$.
    • Power delivered to an RLC series AC circuit is dissipated by the resistance alone.
    • The forced but damped motion of the wheel on the car spring is analogous to an RLC series AC circuit.
    • Calculate the power delivered to an RLC-series AC circuit given the current and the voltage

  • RLC Series Circuit: At Large and Small Frequencies; Phasor Diagram

    • In previous Atoms we learned how an RLC series circuit, as shown in , responds to an AC voltage source.
    • When $Z \approx X_L$, the circuit is almost equivalent to an AC circuit with just an inductor.
    • When $Z \approx X_C$, the circuit is almost equivalent to an AC circuit with just a capacitor.

  • Matrix Inverses

    • $AC = I \Rightarrow B(AC) = B \Rightarrow (BA)C = B \Rightarrow C = B.$
    • The system $A\mathbf{x}= \mathbf{y}$ has at least one solution $x$ for every $\mathbf{y}$ (there might be infinitely many solutions) if and only if the columns span $\mathbf{R}^n$$r=n$ ( $r=n$$r=n$ ), in which case there exists an $m \times n$ right inverse $C$$AC=I_n$ such that $AC=I_n$ .
    • For example, given a right inverse $A$ , then since $AC=I$ , we have $ACy=y$ .

  • Resonance in RLC Circuits

    • Resonance in AC circuits is analogous to mechanical resonance, where resonance is defined as a forced oscillation (in this case, forced by the voltage source) at the natural frequency of the system.
    • The driving AC voltage source has a fixed amplitude V0.
    • An RLC series circuit with an AC voltage source. f is the frequency of the source.

  • Impedance

    • For an RC circuit in , the AC source driving the circuit is given as:
    • where V is the amplitude of the AC voltage, j is the imaginary unit (j2=-1), and $\omega$ is the angular frequency of the AC source.