Experiment to show the application of Kirchhoffs Voltage Law & Kirchhoffs Current Law in series, parallel and combination circuits.

Authors Avatar by firman_alias (student)

CONTENTS


Introduction

In 1845, a German physicist, Gustav Kirchoff developed a pair or set of rules or laws which deal with the conservation of current and energy within electrical circuits. These two rules are commonly known as: Kirchoffs Circuit Laws with one of Kirchof’s laws dealing with the current flowing around a closed circuit, Kirchoffs Current Law, (KCL) while the other law deals with the voltage sources present in a closed circuit, Kirchoffs Voltage Law, (KVL).

Kirchoff’s first law that is KCL  states that the total current or charge entering a junction or node is exactly equal to the charge leaving the node as it has no other place to go except to leave, as no charge is lost within the node. In other words the algebraic sum of all the currents entering and leaving a node must be equal to zero. This idea by Kirchoff is commonly known as the Conservation of Charge.

The term node in an electrical circuit generally refers to a connection or junction of two or more current carrying paths or elements such as cables and components. Also for current to flow either in or out of a node a closed circuit path must exist. We can use Kirchoff's current law when analyzing parallel circuits.

Kirchoff’s second law that is KVL states that in any closed loop network, the total voltage around the loop is equal to the sum of all the voltage drops within the same loop which is also equal to zero. In other words the algebraic sum of all voltages within the loop must be equal to zero. This idea by Kirchoff is known as the Conservation of Energy.


Theory

Kirchoff’s first law state that total current or charge entering a junction or node is exactly equal to the charge leaving the node, so:

∑Iin = ∑Iout

Graphically,

Here, the 3 currents entering the node, I1, I2, I3 are all positive in value and the 2 currents leaving the node, I4 and I5 are negative in value. Then this means we can also rewrite the equation as:

I1 + I2 + I3 - I4  - I5 = 0


Kirchoff’s second law that is KVL states that in any closed loop network, the total voltage around the loop is equal to the sum of all the voltage drops within the same loop, so:

Join now!

∑Vsupply  = ∑Vdrop

VA + VB + VC + VD = 0

Starting at any point in the loop continue in the same direction noting the direction of all the voltage drops, either positive or negative, and returning back to the same starting point. It is important to maintain the same direction either clockwise or anti-clockwise or the final voltage sum will not be equal to zero. We can use Kirchoff's voltage law when analyzing series circuits.

Basic procedure to apply KVL and KCL :

1. Assume all voltages and resistances are given.

2. Label each branch with a branch current.

...

This is a preview of the whole essay