Kirchhoff’s Laws Kirchhoff’s laws are two mathematical rules used in electrical circuit analysis. The first, known as Kirchhoff’s Voltage Law(KVL) states that the sumof the voltages around any loop in an electric circuit must be zero. Basically, this means that when you get back around through the voltage differences in the loop to the point where you started, the voltage there should be what it was before because it can’t have two different values at the same time. KVL follows from the fact that a good conductor must have zero electric field inside it. The voltage, then, must be a constant throughout a wire, so working around the loop to the far end can’t result in a different voltage than the near end. The normal procedure for applying KVL will be shown in more detail in a subsequent discussion, but it basically involves following the flow of current around a loop and, as each circuit element is encountered, writing down a voltage term in a growing equation that will be set equal to zero at the end. Using Ohm’s law, the voltage across resistors is
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Electrical resistance, Electrical impedance, Voltage drop