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Series and parallel capacitors circuits – problems and solutions

Series and parallel capacitors circuits – problems and solutions

1. What is the total charges in the capacitor circuits below (1 μF = 10-6 F)

Known :

Capacitor 1 (C1) = 3 μFSeries and parallel capacitors circuits – problems and solutions 1

Capacitor 2 (C2) = 3 μF

Capacitor 3 (C3) = 3 μF

Capacitor 4 (C4) = 2 μF

Capacitor 5 (C5) = 3 μF

Voltage (V) = 3 Volt

Wanted : Total charge in capacitor circuits (Q)

Solution :

The equivalent capacitor

Capacitor C1, C2 and C3 are connected in series. The equivalent capacitor :

1/C123 = 1/C1 + 1/C2 + 1/C3 = 1/3 + 1/3 + 1/3 = 3/3

C123 = 3/3 = 1 μF

Capacitor C123 and C4 are connected in parallel. The equivalent capacitor :

C1234 = C123 + C4 = 1 + 2 = 3 μF

Capacitor C1234 and C5 are connected in series. The equivalent capacitor :

1/C = 1/C1234 + 1/C5 = 1/3 + 1/3 = 2/3

C = 3/2 μF

C = 3/2 x 10-6 F

The total charges :

The total charges in the equivalent capacitor = the total charges in capacitor circuits :

Q = V C = (3 Volt)(3/2 x 10-6 Farad) = 9/2 x 10-6 Coulomb

Q = 9/2 microCoulomb = 9/2 μC

Q = 4.5 μC

2. If C1 = C2 = 2 μF, C3 = C4 = 1 μF and C5 = 4 μF, determine the total charges in the capacitor circuits as shown in figure below (1 μF = 10-6 F)

Known :

Capacitor 1 (C1) = 2 μF

Capacitor 2 (C2) = 2 μF

Capacitor 3 (C3) = 1 μFSeries and parallel capacitors circuits – problems and solutions 2

Capacitor 4 (C4) = 1 μF

Capacitor 5 (C5) = 4 μF

Voltage (V) = 1.5 Volt

Wanted : The total charges in circuits (Q)

Solution :

The equivalent capacitor :

Capacitor C3 and C4 are connected in parallel. The equivalent capacitor :

C34 = C3 + C4 = 1 + 1 = 2 μF

Capacitor C5, C1, C2 and C34 are connected in series. The equivalent capacitor :

1/C = 1/C5 + 1/C1 + 1/C2 + 1/C34

1/C = 1/4 + 1/2 + 1/2 + 1/2

1/C = 1/4 + 2/4 + 2/4 + 2/4

1/C = 7/4

C = 4/7 μF

C = 4/7 x 10-6 F

The total charges :

The total charges in the equivalent capacitor = the total charges in capacitor circuits :

Q = V C = (1.5 Volt)(4/7 x 10-6 Farad) = 6/7 x 10-6 Coulomb

Q = 6/7 microCoulomb

Q = 6/7 μC

3. Determine the total charges in the capacitor circuits as shown in figure below.

Known :

Capacitor 1 (C1) = 3 μFSeries and parallel capacitors circuits – problems and solutions 3

Capacitor 2 (C2) = 3 μF

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Capacitor 3 (C3) = 4 μF

Capacitor 4 (C4) = 4 μF

Capacitor 5 (C5) = 8 μF

Voltage (V) = 10 Volt

Wanted : The total charge in the circuits (Q)

Solution :

The equivalent capacitor :

Capacitor C1 and C2 are connected in parallel. The equivalent capacitor :

C12 = C1 + C2 = 3 + 3 = 6 μF

Capacitor C3 and C4 are connected in series. The equivalent capacitor :

1/C34 = 1/C3 + 1/C4 = 1/4 + 1/4 = 2/4

C34 = 4/2 = 2 μF

Capacitor C12, capacitor C34 and capacitor C5 are connected in parallel. The equivalent capacitor :

C = C12 + C34 + C5 = 6 + 2 + 8 = 16 μF = 16 x 10-6 Farad

The total electric charges :

The total charges in the equivalent capacitor = the total charges in capacitor circuits :

Q = V C = (10 Volt)(16 x 10-6 Farad) = 160 x 10-6 Coulomb

Q = 160 microCoulomb = 160 μC

20 conceptual questions and answers related to series and parallel capacitors circuits:

1. Question: How are capacitors connected in a series configuration?

Answer: In a series configuration, capacitors are connected end-to-end, so the same current flows through all capacitors.

2. Question: How are capacitors connected in a parallel configuration?

Answer: In a parallel configuration, capacitors are connected across common points or junctions, allowing different currents through each capacitor but maintaining the same voltage across them.

3. Question: How do you calculate the equivalent capacitance for capacitors in series?

Answer: The reciprocal of the equivalent capacitance in a series connection is the sum of the reciprocals of individual capacitances: 1/Cₑq = 1/C₁ + 1/C₂ + … + 1/Cₙ.

4. Question: How do you calculate the equivalent capacitance for capacitors in parallel?

Answer: The equivalent capacitance in a parallel connection is the sum of individual capacitances: Cₑq = C₁ + C₂ + … + Cₙ.

5. Question: What happens to the total capacitance when capacitors are added in series?

Answer: Adding capacitors in series decreases the total or equivalent capacitance.

6. Question: What happens to the total capacitance when capacitors are added in parallel?

Answer: Adding capacitors in parallel increases the total or equivalent capacitance.

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7. Question: How is the charge stored on capacitors connected in series?

Answer: The charge stored on each capacitor in a series connection is the same because the same current flows through all of them.

8. Question: How is the voltage distributed across capacitors connected in series?

Answer: The total voltage is divided among the capacitors in series, and the voltage across each capacitor is inversely proportional to its capacitance.

9. Question: How does the energy stored in a series or parallel combination of capacitors compare to the energy stored in individual capacitors?

Answer: The total energy stored in a combination of capacitors is the sum of the energy stored in individual capacitors, regardless of whether they are in series or parallel.

10. Question: How does the breakdown voltage of a series combination of capacitors compare to individual capacitors?

Answer: In a series combination, the breakdown voltage is typically determined by the capacitor with the lowest breakdown voltage.

11. Question: What is the importance of using capacitors with the same voltage rating in a parallel configuration?

Answer: Using capacitors with the same voltage rating in parallel ensures that each capacitor can handle the common voltage across them, preventing potential damage or failure.

12. Question: Why might you use capacitors in series?

Answer: Capacitors in series can be used to achieve a lower equivalent capacitance or to increase the overall breakdown voltage of the combination.

13. Question: Why might you use capacitors in parallel?

Answer: Capacitors in parallel can be used to increase the total capacitance or to distribute the charge storage across multiple capacitors for applications requiring high charge capacity.

14. Question: How can the total energy stored in a parallel combination of capacitors be calculated?

Answer: The total energy can be calculated as ½ Cₑq V², where Cₑq is the equivalent parallel capacitance, and V is the common voltage.

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15. Question: What is the effect of having unequal capacitances in a series connection?

Answer: In a series connection with unequal capacitances, the voltage distribution will vary, with smaller capacitors having a larger voltage drop across them.

16. Question: How can capacitors in series and parallel be utilized in tuning circuits?

Answer: Series and parallel configurations of capacitors can be used to achieve specific resonant frequencies or phase shifts in tuning circuits, such as in radios or signal processing.

17. Question: What could happen to the equivalent capacitance of a parallel combination if one capacitor fails short-circuited?

Answer: A short-circuited capacitor in parallel would effectively be removed from the circuit, leading to a decrease in the equivalent capacitance.

18. Question: What could happen to the equivalent capacitance of a series combination if one capacitor fails open-circuited?

Answer: An open-circuited capacitor in a series would break the current flow, making the equivalent capacitance zero.

19. Question: How do series and parallel combinations of capacitors affect the impedance in AC circuits?

Answer: Series combinations increase impedance, while parallel combinations decrease it. This behavior can be used to filter or pass specific frequencies in AC circuits.

20. Question: Can you mix series and parallel configurations in the same circuit?

Answer: Yes, series and parallel configurations can be mixed within the same circuit to achieve desired capacitance values and characteristics. The analysis requires applying the rules for both series and parallel combinations.

Understanding the properties and behaviors of capacitors in series and parallel configurations is vital in the design and analysis of electronic circuits, allowing engineers to tailor circuits to specific needs and functions.

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