inductor

Examples of inductor in the following topics:

• 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 .
  • Current lags behind voltage, since inductors oppose change in current.
  • This is considered an effective resistance of the inductor to AC.
  • Explain why the voltage across an inductor "leads" the current in an AC circuit with an inductor

• Energy Stored in a Magnetic Field

  • Thus, inductors oppose change in current by producing a voltage that,in turn, creates a current to oppose the change in magnetic flux; the voltage is proportional to the change in current.
  • For an inductor, that outlet is the magnetic field—the energy stored by an inductor is equal to the work needed to produce a current through the inductor.
  • Let's consider Fig 1 , an example of a solenoid (ℓ: length, N: number of turns, I: current, A: cross-section area) that works as an inductor.
  • Describe behavior of an inductor when the current is changed, and express energy stored in a magnetic field in a form of equation

• RL Circuits

  • A resistor-inductor circuit (RL circuit) consists of a resistor and an inductor (either in series or in parallel) driven by a voltage source.
  • An inductor is a device or circuit component that exhibits self-inductance.
  • We know from Lenz's law that inductors oppose changes in current.
  • It can be shown that the energy stored in an inductor Eind is given by:
  • We know that the current through an inductor L cannot be turned on or off instantaneously.

• Induced Charge

  • If the inductor is positive, electrons migrate toward it, making the uncharged object more negative in that area and positive in the region opposite it.
  • If the inductor is negative, the electrons in the neutral object are repelled, leaving a positive charge near the inductor and a negative charge opposite it .
  • Depending on the sign of the charge of the inductor, electrons will go to or leave the previously uncharged object.
  • Total charge is conserved, and that of the inductor decreases as it transfers charge to its subject.
  • Subjects that can react to inductors include conductors and dielectrics.

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

  • We also learned the phase relationships among the voltages across resistor, capacitor and inductor: when a sinusoidal voltage is applied, the current lags the voltage by a 90º phase in a circuit with an inductor, while the current leads the voltage by 90∘ in a circuit with a capacitor.
  • When $Z \approx X_L$, the circuit is almost equivalent to an AC circuit with just an inductor.
  • This response makes sense because, at high frequencies, Lenz's law suggests that the impedance due to the inductor will be large.
  • A series RLC circuit: a resistor, inductor and capacitor (from left).

• Energy in a Magnetic Field

  • The energy stored by an inductor is equal to the amount of work required to establish the current through the inductor, and therefore the magnetic field.
  • Proof: Power that should be supplied to an inductor with inductance L to run current I through it it given as

• Power

  • The inductor and capacitor have energy input and output, but do not dissipate energy out of the circuit.
  • This assumes no significant electromagnetic radiation from the inductor and capacitor (such as radio waves).
  • Energy within the system goes back and forth between kinetic (analogous to maximum current, and energy stored in an inductor) and potential energy stored in the car spring (analogous to no current, and energy stored in the electric field of a capacitor).

• Inductance

  • A device that exhibits significant self-inductance is called an inductor, and given the symbol in .
  • It is possible to calculate L for an inductor given its geometry (size and shape) and knowing the magnetic field that it produces.

• Different Types of Currents

  • An electrical network is an interconnection of electrical elements such as resistors, inductors, capacitors, transmission lines, voltage sources, current sources and switches.
  • Electrical networks that consist only of sources (voltage or current), linear lumped elements (resistors, capacitors, inductors), and linear distributed elements (transmission lines) can be analyzed by algebraic and transform methods.
  • Analysis of resistive circuits is less complicated than analysis of circuits containing capacitors and inductors.
  • If a capacitor or inductor is added to a DC circuit, the resulting circuit is not, strictly speaking, a DC circuit.

• Inductance

  • A device that exhibits significant self-inductance is called an inductor.