Circuit diagram to understand concept of KVL

Kirchhoff’s Voltage Law (KVL)

This entry is part 9 of 11 in the series Basics of Electricity

The KVL is the best tool to analyse the electrical and even electronic circuits. If you learn KVL properly, you will be able to read all the branches in a circuit like we read a book with all pages in it…! So don’t ignore this topic and the topic of KCL also. It is one of the most important topic in fundamentals of electricity and electronics.

Definition

In Kirchhoff’s Voltage Law, the algebraic addition of all voltage drops in a closed circuit is always equal to zero.

To understand the law consider the following circuit. Here a battery is connected to number of resistors like R1 = 1Ω, R2 = 2Ω, R3 = 3Ω and R4 = 6Ω with battery voltage V = 12V.

The circuit to understand KVL
The circuit to understand KVL

The Maths

Now if we apply Ohm’s Law, we can calculate the total current in the circuit, as follows:

Total resistance of the circuit is: 12Ω. This is because all resistors are in series.

So current flowing through the circuit is: I = V/R
Voltage drop across R1 is: V1 = 1A x 1Ω = 1V
Voltage drop across R2 is: V2 = 1A x 2Ω = 2V
Voltage drop across R3 is: V3 = 1A x 3Ω = 3V
Voltage drop across R4 is: V4 = 1A x 6Ω = 6V
So we can write the equation: V = V1 + V2 + V3 + V4 = 1V + 2V + 3V + 6V = 12V

That is the algebraic addition of all voltages in the circuit, including the battery voltage (V) will be equal to zero.

V1 + V2 + V3 + V4 + (–V) = 1V + 2V + 3V + (–6V) = 0

So the general equation of Kirchhoff’s Voltage Law is given by:

KVL formula

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Prof. Dattaraj Vidyasagar
Prof. Dattaraj Vidyasagar

Author on this website. He is veteran of Core Electronics since last 36+ years. ATL Mentor of Change, Niti Ayog, Govt. of India, Google Certified Educator, International Robotics Trainer and author of 18 books on electronics, robotics, programming languages and web designing... ➤➤

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