LAWS

OHMS LAW

                 

              Ohm's law states that the current through a conductor between two points is directly proportional to the potential difference across the two points. Introducing the constant of proportionality, the resistance, one arrives at the usual mathematical equation that describes this relationship:

where I is the current through the conductor in units of amperes, V is the potential difference measured across the conductor in units of volts, and R is the resistance of the conductor in units of ohms.

 

 

 ^{AMPERS LAW}

 

                 <sup>It relates magnetic fields to electric currents that produce them. Using Ampere's law, one can determine the magnetic field associated with a given current or current associated with a given magnetic field, providing there is no time changing electric field present. In its historically original form, Ampère's circuital law relates the magnetic field to its electric current source.

KIRCHHOFF'S CURRENT LAW</sup> 

This law is also called Kirchhoff's first law, Kirchhoff's point rule, or Kirchhoff's junction rule (or nodal rule).

The principle of conservation of electric charge implies that:

 

At any node (junction) in an electrical circuit, the sum of currents flowing into that node is equal to the sum of currents flowing out of that node, or:

 

The algebraic sum of currents in a network of conductors meeting at a point is zero.

  
 ^{KIRCHHOFF'S VOLTAGE LAW}

This law is also called Kirchhoff's second law, Kirchhoff's loop (or mesh) rule, and Kirchhoff's second rule.

Similarly to KCL, it can be stated as:

Here, n is the total number of voltages measured. The voltages may also be complex:

This law is based on one of the Maxwell equations, namely the Maxwell-Faraday law of induction, which states that the voltage drop around any closed loop is equal to the rate-of-change of the flux threading the loop. The amount of flux depends on the area of the loop and on the magnetic field strength. KVL states the loop voltage is zero. The Maxwell equations tell us that the loop voltage will be small if the area of the loop is small, the magnetic field is weak, and/or the magnetic field is slowly changing.
Routine engineering techniques -- such as the use of coaxial cable and twisted pairs -- can be used to minimize stray magnetic fields and minimize the area of vulnerable loops. Utilization of these techniques creates an arrangement, whereby KVL becomes a useful approximation for situations where its application was imprecise.