2. a) Produce a write-up for the construction and operation of a signal conditioning used for accurate measurement of unknown resistance. This circuit is especially useful for low resistance measurement. Include all suitable diagrams.
Measurement of Resistance:
Resistance is one of the most basic elements encountered in electrical and electronics engineering. The value of resistance in engineering varies from very small value like, resistance of a transformer winding, to very high values like, insulation resistance of that same transformer winding. Although a multimeter works quite well if we need a rough value of resistance, but for accurate values and that too at very low and very high values we need specific methods. In this article we will discuss various methods of resistance measurement. For this purpose we categories the resistance into three classes
Measurement of Low Resistance (<1Ω):
The major problem in measurement of low resistance values is the contact resistance or lead resistance of the measuring instruments, though being small in value is comparable to the resistance being measured and hence causes serious error.
Thus to eliminate this issue small valued resistance are constructed with four terminals. Two terminals are current terminals and other two are potential terminals.
Figure below shows the construction of low resistance.
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