Kirchhoffov zákon – problémy a riešenia

1. Ak R₁ = 2 Ω, R₂ = 4 Ω, R₃ = 6 Ω, určte elektrický prúd prúdi v okruhu nižšie.

Známe:

odpor 1 (R₁) = 2 Ω

Rezistor 2 (R₂) = 4 Ω

Rezistor 3 (R₃) = 6 Ω

Zdroj elektromotorického napätia 1 (E₁) = 9 V

Zdroj elektromotorického napätia 2 (E₂) = 3 V

Hľadá sa: Elektrický prúd (I)

riešenie:

This question relates to Kirchhoffov zákon. How to solve this problem:

Prvá stránka, choose the direction of the current. You can decide the opposite current or direction in the clockwise direction.

Sekunda, when the current through the resistor (R) there is a potential decrease so that V = IR signed negative. tretia, if the current moves from low to high voltage (- to +) then the source of emf (E) signed positive because of the charging of energy at the emf source. If the current moves from high to low voltage (+ to -) then the source of emf (E) signed negative because of the emptying of energy at the emf source.

In this solution, the direction of the current is the same as the direction of clockwise rotation.

– IČ₁ + E₁ – IČ₂ – IČ₃ - E₂ = 0

– 2 I + 9 – 4 I – 6 I – 3 = 0

– 12 I + 6 = 0

– 12 I = – 6

I = -6 / -12

I = 0.5 XNUMX

The electric current flows in the circuit are 0.5 A. The electric current signed positive means that the direction of the electric current is the same as the direction of clockwise rotation. If the electric current is negative, then the electric current is opposite the clockwise direction.

2. Determine the electric current that flows in the circuit as shown in the figure below.

riešenie:

In this solution, the direction of the current is the same as the direction of clockwise rotation.

-20 – 5I -5I – 12 – 10I = 0

-32 – 20I = 0

-32 = 20I

I = -32 / 20

I = -1.6 A

Because the electric current is negative, the direction of the electric current is actually opposite to the clockwise direction. The direction of electric current is not the same as estimation.

3. Determine the electric current that flows in the circuit as shown in the figure below.

riešenie:

In this solution, the direction of current is the same as the direction of clockwise rotation.

– I – 6I + 12 – 2I + 12 = 0

-9I + 24 = 0

-9I = -24

I = 24/9

I = 8 / 3 A

4. An electric circuit consists of four resistors, R₁ = 12 Ohmov, R₂ = 12 Ohmov, R₃ = 3 Ohm and R₄ = 6 Ohm, are connected with source of emf E₁ = 6 voltov, E₂ = 12 Volt. Determine the electric current flows in the circuit as shown in figure below.

Známe:

Rezistor 1 (R₁) = 12 Ω

Rezistor 2 (R₂) = 12 Ω

Rezistor 3 (R₃) = 3 Ω

Rezistor 4 (R₄) = 6 Ω

Zdroj elektromotorického napätia 1 (E₁) = 6 volty

Zdroj elektromotorického napätia 2 (E₂) = 12 volty

Hľadaný: The electric current flows in the circuit (I)

riešenie:

Rezistor 1 (R₁) and resistor 2 (R₂) are connected in parallel. The equivalent resistor :

1/R₁₂ = 1/R₁ +1/R₂ = 1/12 + 1/12 = 2/12

R₁₂ = 12/2 = 6 Ω

In this solution, the direction of current is the same as the direction of clockwise rotation.

– IČ₁₂ - E₁ – IČ₃ - IR₄ + E₂ = 0

– 6 I – 6 – 3 I – 6 I + 12 = 0

– 6I – 3I – 6I = 6 -12

– 15I = – 6

I = -6/-15

I = 2/5 A

5. Determine the electric current that flows in circuit as shown in figure below.

Známe:

Rezistor 1 (R₁) = 10 Ω

Rezistor 2 (R₂) = 6 Ω

Rezistor 3 (R₃) = 5 Ω

Rezistor 4 (R₄) = 20 Ω

Zdroj elektromotorického napätia 1 (E₁) = 8 volty

Zdroj elektromotorického napätia 2 (E₂) = 12 volty

Hľadaný: The electric current that flows in circuit

riešenie:

Rezistor 3 (R₃) and resistor 4 (R₄) are connected in parallel. The equivalent resistor :

1/R₃₄ = 1/R₃ +1/R₄ = 1/5 + 1/20 = 4/20 + 1/20 = 5/20

R₃₄ = 20/5 = 4 Ω

In this solution, the direction of current is the same as the direction of clockwise rotation.

– IČ₁ – IČ₂ - E₁ – IČ₃₄ + E₂ = 0

– 10I – 6I - 8 - 4I + 12 = 0

– 10I – 6I - 4I = 8 - 12

- 20I = - 4

I = -4/-20

I = 1/5 A

I = 0.2 A

6. Determine the electric current that flows in circuit as shown in figure below.

Známe:

Rezistor 1 (R₁) = 1 Ω

Rezistor 2 (R₂) = 6 Ω

Rezistor 3 (R₃) = 6 Ω

Rezistor 4 (R₄) = 4 Ω

Zdroj elektromotorického napätia 1 (E₁) = 12 volty

Zdroj elektromotorického napätia 2 (E₂) = 6 volty

Hľadaný: The electric current that flows in circuit

riešenie:

Rezistor 1 (R₁) and resistor 2 (R₂) are connected in parallel. The equivalent resistor :

1/R₁₂ = 1/R₁ +1/R₂ = 1/1 + 1/6 = 6/6 + 1/6 = 7/6

R₁₂ = 6/7 Ω

The direction of current is the same as the direction of clockwise rotation.

E₁ - Ja R₁₂ - E₂ - Ja R₄ – IČ₃ = 0

12 – (6/7)I – 6 – 4I – 6I = 0

12 – 6 – (6/7)I – 4I – 6I = 0

6 – (6/7)I – 10I = 0

6 = (6/7)I + 10I

6 = (6/7)I + (70/7)I

6 = (76/7)I

(6)(7) = 76I

42 = 76I

I = 42/76

I = 0.5 A