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Electrical receivers connected in series

Source: licencja: CC 0.

Połączenie szeregowe odbiorników

You will learn
  • about connecting resistors in series,

  • define equivalent resistance,

  • check experimentally the formula for equivalent resistance in series connection in English.

Prepare answers to introductory questions for the lesson.

  1. What is electric current?

  2. Introduce Ohm's law.

  3. Define the resistance of the conductor.

  4. How/will the resistance of the conductor change when we increase the voltage applied to it?

When resistors are connected in series?
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Source: GroMar, licencja: CC BY 3.0.
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nagranie abstraktu

The serial connection forces the same current. There is no possibility that a current of different intensity flows through two selected resistors. This would be contrary to the principle of charge conservation.

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Pokaz slajdów – błędne myślenie, gromadzenie się ładunków pomiędzy elementami obwodu. Instrukcja obsługi z poziomu klawiatury: 1. Uruchomienie aplikacji - ENTER, 2. Na każdym ze slajdów czytany jest automatycznie tekst alternatywny po polsku, 3. Przy pierwszym uruchomieniu na pierwszym slajdzie, czytanie tekstu po angielsku - TAB, 4. Przejście między slajdami: do następnego slajdu - TAB, do poprzedniego slajdu - TAB + SHIFT, 5. Przejście do czytania napisu po angielsku - strzałka w górę + strzałka w dół (czyta tekst po angielsku widoczny na slajdzie).
Erroneous thinking, accumulation of charges between elements of the circuit
Source: GroMar, licencja: CC BY 3.0.
Experiment 1
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nagranie abstraktu
Research hypothesis
  • In a series connectionseries connectionseries connection of resistors, the sum of voltages on individual resistors is equal to the voltage supplying the circuit.

1. You will need several different resistors, an ammeter, a voltmeter and a voltage source to perform the experiment.

2. Build the system according to the diagram below.

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Resistors connected in series
Source: GroMar, licencja: CC BY 3.0.
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nagranie abstraktu

3. Perform voltage measurements on individual resistors and supply voltage.

4. Measurements results should be entered into the measurement table.

No.

Number of the resistor

U [V]

Supply voltage [V]

Comments

1

1

2

2

3

3

4

4

5

5

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nagranie abstraktu

5. In order to eliminate errors during the experiment, perform several measurements, preferably each time rearranging the order of the resistors.

6. After completing the experiment, draw the appropriate conclusions.

Conclusion
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nagranie abstraktu

In a series connection of resistors, the sum of voltages on individual resistors is equal to the supply voltage.

U1+U2+U3+U4+U5=Usupply
Equivalent resistance
Definition: Equivalent resistance
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nagranie abstraktu

The equivalent resistanceequivalent resistanceequivalent resistance of the resistors circuit is equal to the resistance of such a resistor which used instead of the resistor circuit will not change the current flowing from the voltage source.

Derivation of the formula for equivalent resistance in a series connectionseries connectionseries connection

Consider a circuit of resistors connected in series.

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Resistors connected in series
Source: GroMar, licencja: CC BY 3.0.
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nagranie abstraktu

Let the voltages on the resistors equal respectively: U1,U2,U3,U4,U5. The current flows in the system with the intensity I. Under Ohm's law we have:

U1=I·R1
U2=I·R2
U3=I·R3
U4=I·R4
U5=I·R5

If we use substitute equivalent resistanceequivalent resistanceequivalent resistance instead of all resistors, then:

Usupply=IRequiv

Substituting above relations into the formula:

U1+U2+U3+U4+U5=Usupply

after simplification it leads to the final result:

R1+R2+R3+R4+R5=Requiv
Final conclusion
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nagranie abstraktu

In a series connectionseries connectionseries connection of resistors, equivalent resistanceequivalent resistanceequivalent resistance is the sum of resistances of individual resistors.

Experiment 2
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nagranie abstraktu
Research hypothesis
  • In a series connectionseries connectionseries connection of resistors, equivalent resistance is the sum of resistances of individual resistors.

1. You will need several different resistors, an ammeter, a voltmeter and a voltage source to perform the experiment.

2. Build the system according to the diagram below.

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

3. In the way known to you, determine the resistances of individual resistors.

4. Calculate the total resistance of the resistor system.

5. Enter the results into the measurement table.

Tabela zbudowana z siedmiu wierszy i czterech kolumn. W pierwszym wierszu: No., Number of the resistor, R [Ω] - opór mierzony w omach, Comments. W drugim wierszu: 1, 1, pusta komórka, pusta komórka. W trzecim wierszu: 2, 2, pusta komórka, pusta komórka. W czwartym wierszu: 3, 3, pusta komórka, pusta komórka. W piątym wierszu: 4, 4, pusta komórka, pusta komórka. W szóstym wierszu: 5, 5, pusta komórka, pusta komórka. W siódmym wierszu: pusta komórka, Total resistance, pusta komórka, pusta komórka.
Tabela zbudowana z siedmiu wierszy i czterech kolumn. W pierwszym wierszu: No., Number of the resistor, R [Ω] - opór mierzony w omach, Comments. W drugim wierszu: 1, 1, pusta komórka, pusta komórka. W trzecim wierszu: 2, 2, pusta komórka, pusta komórka. W czwartym wierszu: 3, 3, pusta komórka, pusta komórka. W piątym wierszu: 4, 4, pusta komórka, pusta komórka. W szóstym wierszu: 5, 5, pusta komórka, pusta komórka. W siódmym wierszu: pusta komórka, Total resistance, pusta komórka, pusta komórka.
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nagranie abstraktu

6. In order to eliminate errors during the experiment, perform several measurements, preferably each time rearranging the order of the resistors.

7. After completing the experiment, draw the appropriate conclusions.

Conclusion

If the experiment was performed correctly, then within the limits of measurement errors:

R1+R2+R3+R4+R5=Rtotal=Requiv

It is, therefore, a confirmation of the formula derived theoretically.

Summary
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nagranie abstraktu
  • In the series connectionseries connectionseries connection, a current I flows through the closed electrical circuit. It is the same in any point of the serial circuit.

  • The voltage between the ends of the resistors connected in series is equal to the sum of the voltages between the ends of each of them.

  • The total resistance (equivalent resistanceequivalent resistanceequivalent resistance) in the series connection is the sum of the resistances of individual resistors:

    R=R1+R2+R3+...

Exercises

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Exercise 1
Wersja alternatywna ćwiczenia: Determine which sentences are true. Możliwe odpowiedzi: 1. The equivalent resistance is always greater than any of the resistances used in a series connection., 2. The equivalent resistance is always smaller than any resistance used in a series connection., 3. The current flowing through each resistor is the same in a series connection., 4. The voltage on each resistor is the same in a series connection.
Exercise 2

Given a circuit as shown below.

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Source: GroMar, licencja: CC BY 3.0.

The resistances of the resistors are respectively RIndeks dolny 1 = 10 Ω, RIndeks dolny 2 = 20 Ω, RIndeks dolny 3 = 30 Ω. It was found that on a certain resistor the smallest possible voltage is equal to 10 V.

Which resistor has the highest voltage and how much is it?

Exercise 3

Explain in English what a voltage dividervoltage dividervoltage divider is and how it works.

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Exercise 4
Wersja alternatywna ćwiczenia: Indicate which pairs of expressions or words are translated correctly. Możliwe odpowiedzi: 1. opór zastępczy - equivalent resistance, 2. podzielnik napiecia - series connection, 3. spadek napięcia - voltage drop, 4. zasada zachowania ładunku - principle of charge conservation, 5. połączenie szeregowe - voltage divider
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

equivalent resistance
equivalent resistance

opór zastępczy

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wymowa w języku angielskim: equivalent resistance
principle of charge conservation
principle of charge conservation

zasada zachowania ładunku

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wymowa w języku angielskim: principle of charge conservation
series connection
series connection

połączenie szeregowe

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wymowa w języku angielskim: series connection
voltage divider
voltage divider

podzielnik napiecia

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wymowa w języku angielskim: voltage divider
voltage drop
voltage drop

spadek napięcia

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wymowa w języku angielskim: voltage drop

Keywords

equivalent resistanceequivalent resistanceequivalent resistance

series connectionseries connectionseries connection

voltage dropvoltage dropvoltage drop