Kirchoff Laws

Kirchoff law consists of two laws relating to electronic circuits.

The two laws are named after Gustav Kirchoff, who described them in 1845.

Law one deals with Current (I) within a circuit, and law two deals with Potential Difference which is also commonly known as Voltage (V).

LAW 1 – THE CURRENT LAW

The current entering any junction in a circuit (i.e a component connection point on a PCB) is equal to the current leaving that junction point.

To state this law algebraically we can state:

Before you run away screaming, I will explain how to understand the algebraic equation above.

The thing that looks like a bit like a drunken ‘E’  is called an epsilon. It means the total addition of the currents entering and existing the point in a circuit.

‘I’ is the symbol for Current

‘n’ is the total number of connections (or branches) flowing towards, or away from the particular point in the circuit (known as the node point).

LAW 2 – THE VOLTAGE LAW

The Sum of all the voltages around the loop is equal to zero.

V1+V2+V3 – V4 = 0

Where V4 is the Voltage supply.