In this article, we will look in detail at Kirchhoff's law for voltages and Kirchhoff's law for currents and examine their principles and applications. We will examine how these laws form the basis of circuit analysis and provide a solid framework for understanding the behavior of electrical networks. By understanding the concepts and techniques associated with KVL and KCL, readers will gain valuable information about electrical circuit analysis and be equipped with powerful tools for solving complex electrical problems.
Kirchhoff's current law (KCL)
Consider a node. The figure shows the complex network. At this junction when I 1 =2A, I 2 =4A, and I 3 =1A, then the current I must be determined 4, We say that the sum of the current flowing is 4+4=8A, while the sum of the current leaving of the circuit is 2+I. 4 A
So I 4 = 6A.
This study of the currents entering and leaving the circuit is nothing more than the application of Kirchhoff's current law. This KCL (Kirchhoff's law) can be expressed as follows:
The sum of the currents flowing toward a junction is equal to the sum of the currents flowing away from the junction.
This law can also be expressed as follows:
The algebraic sum of all currents at point O is always zero. The letter means algebraic with regard to the signs of various currents.
ΣI at node O = 0
The figure above shows that the currents I 1 and I 2 are positive while I 3 and I 4 are negative.
Application of KCL, ΣI at node O = 0
I 1 + I 2 - I 3 - I 4 = 0
I.e. ME 1 + ME 2 = ME 3 + ME 4
Kirchhoff's law is very useful in simplifying networks.
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PN junction diode
Kirchhoff Voltage Law (KVL):
In any network, the algebraic sum of voltage drops in the circuit elements of a closed circuit is equal to the algebraic sum of all branch voltages around a closed circuit or closed circuit and is always zero.
To create a closed path Σv=0
The law states that if someone starts at a certain point on a closed path and continues tracing and detecting all potential changes (ascents or descents) in a certain direction until they reach the starting point again, they must be at the same potential, with which he began to trace the closed path.
The sum of all potential risks must equal the sum of all potential waste when following a closed loop. The total potential change along a closed path is always zero.
This law is very useful in network loop analysis.
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Types of semiconductors
Drawing conventions to observe when using KVL
Voltage drop occurs across the resistor when a current flows through the resistor. The polarity of this voltage drop always depends on the direction of the current. Current always flows from the highest to the lowest potential.
In Fig. (a), current I flows from right to left. Therefore, point B has a higher potential than point A, as shown in Fig.
In Fig. (b), current I flows from left to right. Therefore, point A is at a higher potential than point B, which is also shown.
Once we have marked all these polarities in the given circuit, we can apply KVL to any closed path in the circuit.
Now, when tracing a closed path, if we go from the terminal marked -ve to the terminal marked +ve, this voltage must be considered positive. This is called potential increase.
For example, if the branch AB is drawn from A to B, the fall above it should be considered a rise and taken into account as +IR when writing the equations.
When tracing a closed path, if we move from the terminal marked + to the terminal marked -, then this voltage must be considered negative. This is called voltage drop.
For example, in Figure (a), when writing the equations, the branch drawn from B to A should be considered negative, that is, -IR.
Similarly in Fig (b): when the branch is drawn from A to B, there is a voltage drop and the term must be written negative as -IR when writing the equation. As the branch is drawn from B to A, there is an increase in voltage and the term must be written positive as +IR when writing the equation.
In Fig. (b), current I flows from left to right. Therefore, point A is at a higher potential than point B as shown.
