Resistor capacitance which affect the relation between voltage and current in alternating current circuits. The ohm (symbol: Ω) is the SI unit of electrical resistance, named after Georg Simon Ohm. An ohm is equivalent to a volt per ampere. Since resistors are specified and manufactured over a very large range of values, the derived units of milliohm (1 mΩ = 10 Ω), kilohm (1 kΩ = 10 Ω), and megohm (1 MΩ = 10 Ω) are also in common usage. The total resistance of resistors connected in series is the sum of their individual resistance values. The total resistance of resistors
Contact resistance one pair of leads is used to inject the measurement current while a second pair of leads, in parallel with the first, is used to measure the potential drop across the device. In the four-probe case, there is no potential drop across the voltage measurement leads so the contact resistance drop is not included. The difference between resistance derived from two-lead and four-lead methods is a reasonably accurate measurement of contact resistance assuming that the leads resistance is much smaller. Specific contact resistance can be obtained by multiplying by contact area. It should also be noted that the contact resistance