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Charging bodies by contact

Source: licencja: CC 0.

Elektryzowanie ciał przez dotyk

You will learn
  • the difference in the structure of a conductor and insulator,

  • understand the nature of charging bodies by contact in English.

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nagranie abstraktu

Answer the introductory questions for the lesson.

  1. Present in brief the structure of the atom.

  2. What are electrons and where are they located?

  3. Does each atom have the same number of electrons?

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nagranie abstraktu

Each body is made up of many atoms in which the number of protons and electrons is the same. Additional electrons can be led to such a body, and then such a body is endowed with a negative electric charge. If we take electrons from the valence shells from the atom, we say that the body is endowed with a positive electric charge. It must be remembered that protons can not be detached or delivered to the atom. Only a change in the number of electrons can lead to electrified body.

Conductor
Definition: Conductor
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nagranie abstraktu

The conductor is a body in which electrons orbiting the atomic nucleus are weakly bound to the atomic nucleus. The electrons in the outermost orbits can practically move in the entire body volume.

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In conductors, electrons can move practically in the entire volume of the conductor
Source: GroMar, licencja: CC BY 3.0.
Insulator
Definition: Insulator
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nagranie abstraktu

An insulator is called every body in which electrons orbiting the atomic nucleus are very strongly related to this nucleus and therefore can not move inside the body. In certain situations they can move slightly inside the atom.

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In insulators, electrons are permanently bound to the atom's parent nucleus
Source: GroMar, licencja: CC BY 3.0.
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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. Atomy wzięte są w klamrę oznaczoną 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. Atomy wzięte są w klamrę oznaczoną 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 atom's 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.
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nagranie abstraktu

Chargingcharging Charging is the process of accumulation of an excess of charge of the same sign in a given body.

Chargingcharging Charging by contactcontactcontact occurs when we touch at least two bodies with each other, of which at least one is charged. When the bodies come into contact, electrons flow from one body to another.

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Charging bodies by contact
Source: GroMar, licencja: CC BY 3.0.
Stages of charging by contact
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nagranie abstraktu
  • Positively electrified glass rod (shortage of electrons) approaches the neutral metal ball, located on the top of the electroscope (a sphere in which there is no excess or underflow of electrons).

  • After contact between two bodies, some of the electrons from the sphere will flow to the glass rod. The glass rod will still be positively charged, but this charge will be smaller. In contrast, the metal part of the electroscope will obtain a positive charge. (Due to the construction of insulators, the change of charge on the glass rod is local.) To change the electrification state of a larger part of the glass rod, it should be moved over the sphere of the electroscope.

  • Leaves of the electroscope will rise (repulsion of like charges).

Characteristics of charging by contact
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nagranie abstraktu
  • Electrifying the bodies by touch occurs when we touch bodies with each other, at least one of which is endowed with an electric charge.   

  • As a result of contact, some of the electrons pass from the body on which there are more of them to the second, where there are fewer of them.   

  • The distribution of charge between the body is such that the sum of charges after contact of the bodies is equal to the charge of the charged body before contact with the electrically inert body.

  • On both bodies, after contact, it will be the same load if they are identical (e.g. two identical conductor balls).

  • It is static electricity.

Only conductors can be charged by contactcontactcontact.

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Po lewej stronie ilustracji interaktywnej narysowany jest poziomy prostokąt z zaokrąglonymi rogami i ośmioma znakami minus wewnątrz po prawej stronie, opisany numerem 1. Po jego prawej stronie koło z czterema znakami plus po lewej stronie i czterema znakami minus po prawej stronie, opisane numerem 2. Od koła ukośnie do góry narysowana jest linia do linii poziomej. Zaznaczona strzałka od prostokąta do koła. Po prawej stronie ilustracji interaktywnej narysowany jest poziomy prostokąt z zaokrąglonymi rogami i czterema znakami minus wewnątrz po prawej stronie. Jego prawy bok styka się z kołem z czterema znakami minus po prawej stronie. Miejsce styku oznaczone numerem 3. Od koła ukośnie do góry narysowana jest linia do linii poziomej. Na ilustracji widoczne są numery, a na nich podpisy. 1. body with negative charge {audio}, 2. movement of charges in a neutral body {audio}, 3. distribution of charges after charging {audio}.
Flow of charge during charging by contact
Source: GroMar, licencja: CC BY 3.0.
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nagranie abstraktu

During charging, the total chargetotal chargetotal charge is always conserved. Below are examples of charge values of two identical bodies before and after chargingcharging charging by contactcontactcontact.

Body A (I)

Body B (I)

Body A (II)

Body B (II)

0

-20 mC

-10 mC

-10 mC

0

+20 mC

+10 mC

+10 mC

+5 mC

-15 mC

-5 mC

-5 mC

Summary
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nagranie abstraktu
  • Chargingcharging Charging by contactcontactcontact occurs when we touch at least two bodies with each other, of which at least one is charged. When the bodies come into contact, electrons flow from one body to another.

  • Electrons move from one body to the other, thus causing chargingcharging charging the second body and the reduction of charge in the first body. According to the law of electric chargeelectric chargeelectric charge conservation, the total chargetotal chargetotal charge before contact must be equal to the total charge after contact.

Exercises

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Exercise 1
Wersja alternatywna ćwiczenia: Determine which sentences are true. Możliwe odpowiedzi: 1. During charging by contact, only the negative charge can flow., 2. In the process of charging by contact, a charge of the same sign as the existing one is generated., 3. In the process of charging by contact, the total charge decreases due to the flow of this charge to another body., 4. Only insulators can be charged by contact because only for them the flow of charge from one body to another is possible.
zadanie
Source: GroMar, licencja: CC BY 3.0.
Exercise 2

If two spheres with different radii are in contact with each other, the charge will not evenly split into both spheres in the process of charging. It turns out that the bigger the radius of the sphere the bigger the charge will be on it. Mathematically, you can write that charge Q is proportional to the radius R (Q ~ R). A metal sphere with a radius of 4 cm having a charge of 18 μC was brought in contact with an electrically neutral sphere with a radius of 2 cm. Determine how much charge a sphere with a smaller radius will receive in the process of charging by contact.

Exercise 3

The sphere made of an insulator is charged on the surface with a certain charge. Write in English how you can neutralize this charge.

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Exercise 4
Wersja alternatywna ćwiczenia: Indicate which pairs of expressions or words are translated correctly. Możliwe odpowiedzi: 1. ładunek elektryczny - electric charge, 2. elektryzowanie - charging, 3. dotyk - contact, 4. ładunek sumaryczny - charge flow, 5. przepływ ładunku - total charge
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

electric charge
electric charge

ładunek elektryczny

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wymowa w języku angielskim: electric charge
charging
charging

elektryzowanie

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wymowa w języku angielskim: charging
contact
contact

dotyk

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wymowa w języku angielskim: contact
total charge
total charge

ładunek sumaryczny

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wymowa w języku angielskim: total charge
charge flow
charge flow

przepływ ładunku

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wymowa w języku angielskim: charge flow

Keywords

electric chargeelectric chargeelectric charge

chargingcharging charging

contactcontactcontact