What is a simple way to explain Kirchhoff Laws?

In 1845, German physicist Gustav

Kirchhoff first described two laws that

became central to electrical engineering. The

laws were generalized from the work of

Georg Ohm. The laws can also be derived

from Maxwell’s equations, but were

developed prior to Maxwell’s work.

The following descriptions of Kirchhoff's

Laws assume a constant current. For time-

varying current, or alternating current, the

laws must be applied in a more precise

method.

Kirchhoff's Current Law

Kirchhoff's Current Law, also known as

Kirchhoff's Junction Law and Kirchhoff's

First Law, defines the way that electrical

current is distributed when it crosses

through a junction - a point where three or

more conductors meet. Specifically, the law

states that:

The algebraic sum of current into any

junction is zero.

Since current is the flow of electrons

through a conductor, it cannot build up at a

junction, meaning that current is conserved:

what comes in must come out. When

performing calculations, current flowing

into and out of the junction typically have

opposite signs. This allows Kirchhoff's

Current Law to be restated as:

The sum of current into a junction

equals the sum of current out of the

junction.

Kirchhoff's Current Law in action

In the picture to the right, a junction of four

conductors (i.e. wires) is shown. The

currents i2 and i3 are flowing into the

junction, while i1 and i4 flow out of it. In

this example, Kirchhoff's Junction Rule yields

the following equation:

i2 + i3 = i1 + i4

Kirchhoff's Voltage Law

Kirchhoff's Voltage Law describes the

distribution of voltage within a loop, or

closed conducting path, of an electrical

circuit. Specifically, Kirchhoff's Voltage Law

states that:

The algebraic sum of the voltage

(potential) differences in any loop must

equal zero.

The voltage differences include those

associated with electromagnetic fields

(emfs) and resistive elements, such as

resistors, power sources (i.e. batteries) or

devices (i.e. lamps, televisions, blenders, etc.)

plugged into the circuit.

Kirchhoff's Voltage Law comes about

because the electrostatic field within an

electric circuit is a conservative force field.

As you go around a loop, when you arrive at

the starting point has the same potential as

it did when you began, so any increases and

decreases along the loop have to cancel out

for a total change of 0. If it didn't, then the

potential at the start/end point would have

two different values.

Positive and Negative Signs in Kirchhoff's

Voltage Law

Using the Voltage Rule requires some sign

conventions, which aren't necessarily as

clear as those in the Current Rule. You

choose a direction (clockwise or counter-

clockwise) to go along the loop.

When travelling from positive to negative (+

to -) in an emf (power source) the voltage

drops, so the value is negative. When going

from negative to positive (- to +) the voltage

goes up,

Kirchhoff's present regulation, often referred to as Kirchhoff's Junction regulation and Kirchhoff's First law, defines the best way that electrical current is distributed when it crosses via a junction - a factor where three or extra conductors meet. Above all, the legislation states that: The algebraic sum of current into any junction is zero. Because current is the drift of electrons by way of a conductor, it can't construct up at a junction, which means that current is conserved: what is available in ought to come out. When performing calculations, present flowing into and out of the junction by and large have opposite signs. This permits Kirchhoff's present legislation to be restated as: The sum of current right into a junction equals the sum of current out of the junction.