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Electric conductors and insulators. Electric current flow in conductors

Source: licencja: CC 0.

Przewodniki i izolatory prądu elektrycznego. Przepływ prądu w przewodnikach

You will learn
  • indicate the difference in the structure of conductors and insulators,

  • formulate the conditions of electric current flow in English.

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nagranie abstraktu

Answer the introductory questions for the lesson.

  1. What is each body built of?

  2. Describe the structure of the atom.

  3. What determines the number of electrons orbiting the atomic nucleus?

Conductor
Definition: Conductor
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nagranie abstraktu

The conductorconductorconductor is a body in which electrons orbiting the atomic nucleus are weakly bound to the atomic nucleus. The electrons in the outermost orbits can move freely throughout the body.

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Conductor
Source: GroMar, licencja: CC BY 3.0.
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nagranie abstraktu
Let's take a closer look at the structure of conductors
  • The most commonly used conductors are metals. Atoms are placed in them regularly. They have no freedom of movement. The force of their mutual interactions holds them at constant distances and allows only slight vibrations.

  • The electrons that are farthest from the atomic nucleus (so‑called valence electrons) can easily detach themselves from their atoms, and because the forces acting on these electrons from all metal atoms are balanced, these electrons can move freely in the entire volume of the conductorconductorconductor.

  • They belong to the entire conductor, not just the parent atoms. Other electrons, those closer to the atomic nuclei, are unable to break free and remain at their parent atoms.

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The electrons located on the farthest orbits (so-called valence electrons) can move in the entire volume of the conductor. They form so-called electron gas and allow the flow of electric current
Source: GroMar, licencja: CC BY 3.0.
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nagranie abstraktu

So it is in metals. But not only there the charges are free to move. Another example of conductors are electrolytes, i.e. solutions of acids, bases and salts. Water molecules act on the molecules of acids, bases and salts like scissors - they cut them into parts, one of which is a positive ion and the other a negative ion. Like water molecules, they are free to move. In a liquid (not like in metals) there are no forces that could hold particles in place.

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The chaotic ion movement in the liquid also allows electric current to flow
Source: GroMar, licencja: CC BY 3.0.
Insulator
Definition: Insulator
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nagranie abstraktu

The insulatorinsulatorinsulator is a body in which electrons orbiting the nucleus are strongly bound to the nucleus and absolutely cannot move throughout the body. In certain situations, they can move slightly within the volume of an atom.

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Insulator
Source: GroMar, licencja: CC BY 3.0.
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nagranie abstraktu

Insulators are materials whose internal structure is characterized by the fact that electrons are very strongly bound to atoms. They cannot easily break away from atoms and do not have the possibility of free movement within the body. They can be charged by friction - then some electrons detach from atoms and move to the surface of other body. Insulators include among others glass, porcelain, plastic, wood, rubber, distilled water, dry air.

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W górnej części ilustracji interaktywnej przedstawione jest schematycznie sześć atomów: kółko ze znakiem plus, wokół niego dwa okręgi, na każdym z nich jest kółko ze znakiem minus. Jeden z atomów oznaczony jest numerem 1, jedno kółko ze znakiem minus oznaczone jest numerem 2. W dolnej części ilustracji interaktywnej przedstawione jest jest schematycznie osiem atomów: kółko ze znakiem plus, wokół niego okrąg, na którym jest kółko ze znakiem minus. Kółka ze znakiem minus znajdują się także w wolnej przestrzeni między atomami. Jeden z atomów oznaczony jest numerem 3, jedno kółko ze znakiem minus oznaczone jest numerem 4. Na ilustracji widoczne są numery, a na nich podpisy. 1. insulators {audio}, 2. electrons move only around the parent nucleus {audio}, 3. conductors {audio}, 4. electrons move in the entire volume {audio}.
Differences between conductors and insulators
Source: GroMar, licencja: CC BY 3.0.
Electric current
Definition: Electric current
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nagranie abstraktu

We already know that bodies, which as a whole are electrically neutral, hide within themselves charges of both signs. We also know that there are bodies called conductors, where some of these charges (electrons or ions) are free to move. The movement of these charge carriers is chaotic. However, if an external factor arranges the movement of charges, we deal with electric currentelectric currentelectric current.

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Source: GroMar, licencja: CC BY 3.0.
Summary
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nagranie abstraktu

Depending how easy bodies conduct electricity, we divide them into conductors and insulators.

  • The internal structure determines the electrical properties of the bodies. Valence electrons play an important role.

  • The valence electron is the electron located on the last (outermost) shell of the atom. The number of valence electrons and how strongly they are bound to the nucleus of an atom affect many of the physical properties of the element, including thermal and electrical conductivity.

  • The conductivity can be electronic or ionic.

  • The electric current conductorconductorconductor is the body in which the electric charge is carried by the valence electrons. The metallic conductors include mainly metals, like copper, aluminium, iron and gold.

  • In the ionic conductor, the charge carriers are positive or negative ions. The flow of electric currentelectric currentelectric current is accompanied by visible mass transport. Electrolytic conductivity occurs in liquids, solids and gases.

  • An insulatorinsulatorinsulator is a substance that does not conduct electricity and is characterized by low concentration of charge carriers. Insulators include among others: rubber, polystyrene, dry wood, distilled water and dry air.

Exercises

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Exercise 1
Wersja alternatywna ćwiczenia: Determine which sentences are true. Możliwe odpowiedzi: 1. In metallic conductors there are free protons that can move freely in the entire volume of the conductor., 2. In metallic conductors there are free electrons that can move freely in the entire volume of the conductor., 3. There are no electrons in the insulators and therefore the electric current cannot flow through the insulator., 4. In insulators, electrons can only move within the region of the parent atom.
zadanie
Source: GroMar, licencja: CC BY 3.0.
Exercise 2

Illustration shows the construction of a typical cable used in home installations. Explain what function copper wire has in this cable and what function has insulation around this conductor.

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A typical electrical cable used in home installations
Exercise 3

Write in English a note about the use of insulators and conductors. Indicate the sources from which you got information.

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Exercise 4
Wersja alternatywna ćwiczenia: Indicate which pairs of expressions or words are translated correctly. Możliwe odpowiedzi: 1. przewodnik - conductor, 2. izolator - insulator, 3. wolne elektrony - free electrons, 4. prąd elektryczny - free electrons, 5. ruch ładunku - electric current
zadanie
Source: GroMar, licencja: CC BY 3.0.
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Interaktywna gra, polegająca na łączeniu wyrazów w pary w ciągu jednej minuty. Czas zaczyna upływać wraz z rozpoczęciem gry. Jeden ruch to odkrywanie najpierw jednej potem drugiej karty z wyrazem. Każdy wyraz jest odczytywany. Kolejny ruch to odkrywanie trzeciej i czwartej karty. W ten sposób odsłuchasz wszystkie wyrazy. Nawigacja z poziomu klawiatury za pomocą strzałek, odsłuchiwanie wyrazów enterem lub spacją. Znajdź wszystkie pary wyrazów.
Source: Zespół autorski Politechniki Łódzkiej, licencja: CC BY 3.0.

Glossary

conductor
conductor

przewodnik

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wymowa w języku angielskim: conductor
insulator
insulator

izolator

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wymowa w języku angielskim: insulator
free electrons
free electrons

wolne elektrony

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wymowa w języku angielskim: free electrons
electric current
electric current

prąd elektryczny

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wymowa w języku angielskim: electric current
charge movement
charge movement

ruch ładunku

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wymowa w języku angielskim: charge movement

Keywords

conductorconductorconductor

insulatorinsulatorinsulator

free electronsfree electronsfree electrons