Kirchhoff's Voltage Law

Definition

Kirchhoff's Voltage Law (KVL) is a fundamental principle in electrical circuit theory that states the algebraic sum of the voltage drops around any closed loop in an electrical circuit must be equal to zero. It is one of the two key laws, along with Kirchhoff's Current Law, that govern the behavior of electrical circuits.

5 Must Know Facts For Your Next Test

1. Kirchhoff's Voltage Law states that the algebraic sum of the voltage drops around any closed loop in a circuit must be zero.
2. The voltage drops around a closed loop can be positive or negative, but the sum of all the voltage drops must equal zero.
3. Kirchhoff's Voltage Law is applicable to both series and parallel circuits, but it is most commonly used in the analysis of series circuits.
4. The voltage drops in a series circuit are additive, meaning the sum of the voltage drops across all the components in the loop must be equal to the total voltage supplied to the circuit.
5. Kirchhoff's Voltage Law is a consequence of the conservation of energy principle, which states that energy cannot be created or destroyed, only transformed or transferred.

Review Questions

• Explain how Kirchhoff's Voltage Law relates to the behavior of series circuits.
  • In a series circuit, the components are connected end-to-end, forming a single loop. According to Kirchhoff's Voltage Law, the sum of the voltage drops across all the components in this loop must be equal to the total voltage supplied to the circuit. This means that the voltage drops across each component in the series circuit are additive, and the total voltage drop around the loop must equal the source voltage. This relationship is a fundamental principle for analyzing and solving series circuit problems.
• Describe the role of Kirchhoff's Voltage Law in the conservation of energy principle.
  • Kirchhoff's Voltage Law is a direct consequence of the conservation of energy principle, which states that energy cannot be created or destroyed, only transformed or transferred. In an electrical circuit, the sum of the voltage drops around a closed loop must be zero because any energy lost in one part of the circuit must be gained in another part. This ensures that the total energy in the circuit is conserved, with no net energy gain or loss. The application of Kirchhoff's Voltage Law to circuit analysis helps verify that energy is being properly accounted for and that the circuit is behaving in accordance with the fundamental laws of physics.
• Analyze how Kirchhoff's Voltage Law can be used to solve for unknown voltages in a series circuit.
  • When applying Kirchhoff's Voltage Law to a series circuit, you can use the fact that the sum of the voltage drops around the closed loop must be equal to the total voltage supplied to the circuit. This relationship can be used to solve for unknown voltages in the circuit. By writing an equation that sets the sum of the known and unknown voltage drops equal to the total source voltage, and then rearranging the equation, you can isolate and solve for the unknown voltages. This process is a crucial step in the analysis and design of series circuits, as it allows you to determine the voltage across each component based on the known circuit parameters.

Related terms

Closed Loop: A closed loop in an electrical circuit is a continuous path that allows the flow of current to return to its starting point, forming a complete circuit.

Voltage Drop:

The voltage drop is the potential difference across a component or section of a circuit, which is the result of the current flowing through the resistance of that component or section.

Series Circuits: A series circuit is an electrical circuit in which components are connected end-to-end, allowing only one path for the current to flow through all the components.