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3.7 Inductances

Besides resistors and capacitors, we highlight another type of passive element commonly used in circuit abstraction: inductors. We commonly use some symbols to represent inductances (Fig. 3.17).

Diagram showing four types of inductors. From left to right: a simple coil, a coil with a solid core, a coil with a dashed core indicating a variable inductor, and a coil with an arrow through it representing an adjustable inductor.

Fig. 3.17 Inductance symbols. Source From wikicommons under free to use license [7]

As we have seen, a capacitor models the effect of the electric field. Correspondingly, the inductance models the effect of magnetic field. Inductances or coils are passive components that consist of a conductive wire that is often wound around a ferromagnetic core material, which is made of magnetic sheet or ferrite.

Question Then how do we define inductance? Inductance is a property that occurs in an inductor when electric current flows through it, provoking that a magnetic flux appears according to physics laws. In essence, inductance is the number of flux linkages per current unit (amperes).

练习题

Which type of circuit element is an inductor, and what physical phenomenon does it model?

A. Active element that models electric field effects

B. Passive element that models magnetic field effects

C. Passive element that models electric field effects

D. Active element that models magnetic field effects

What materials are commonly used for the core of an inductor?

A. Plastic and glass

B. Copper and aluminum

C. Magnetic sheet or ferrite

D. Carbon and silicon

According to the standard symbols for inductances, which symbol would represent a variable inductor?

A. A simple coil with no core indication

B. A coil with a solid core

C. A coil with a dashed core

D. A coil with an arrow through it

Which of the following statements about inductors are correct?

A. Inductors are passive circuit elements

B. Inductors model the effect of electric fields

C. Inductors typically consist of conductive wire wound around a ferromagnetic core

D. Inductors and capacitors are both passive elements used in circuit abstraction

A capacitor models the effect of the magnetic field, while an inductance models the effect of the electric field.

Inductance is a property that occurs in an inductor when electric current flows through it, causing magnetic flux to appear.

Inductance is defined as the number of flux linkages per unit of voltage.

While a capacitor models the effect of the electric field, an inductance models the effect of the ___ field.

In essence, inductance is the number of ___ per current unit (amperes).

Explain the fundamental difference between how capacitors and inductors store energy, relating each to the type of field they model.

A capacitor models the effect of the electric field in a circuit and stores energy in the form of voltage across its plates. Which type of passive circuit element models the effect of the magnetic field?

A. Resistor

B. Inductor

C. Capacitor

D. Diode

Unlike resistors which dissipate energy, both capacitors and inductors are passive elements that store energy rather than dissipate it.

While a capacitor models the effect of the ___ field and stores energy as voltage, an inductance models the effect of the magnetic field and produces magnetic flux when current flows through it.

Which of the following statements correctly describe the characteristics of resistors, capacitors, and inductors as circuit elements?

A. All three are passive elements commonly used in circuit abstraction

B. Capacitors and inductors store energy while resistors dissipate energy

C. Capacitors model electric field effects while inductors model magnetic field effects

D. Inductance is defined as the number of flux linkages per unit of current

E. Capacitors and resistors both store energy in magnetic fields

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