Measuring resistance using Wheatstone bridge

Question

Can we measure the resistance of the order of 0.160 ohm using a Wheatstone bridge? Support your answer with reasoning.

 

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Physics Sudhanshu Kumar 6 months 1 Answer 195 views 0

Answer ( 1 )

  1. No, the resistance of the connecting wires and at the junctions of the meter bridge and other terminals is itself of the order of the resistance to be measured. It would create uncertainty in the measurement of the low resistance.

    The low resistance however can be determined by using a meter bridge of wire of resistance of about 0.5 Ohm and homogeneous composition and uniform cross-section area throughout, making the second arm resistance of magnitude 0.16 Ohm using standard resistance. The reading should be taken by interchanging the arms and calculating the mean.
    Using thick copper wires for connections, a voltmeter of infinite resistance and a sensitive ammeter of almost zero resistance can be used to measure the potential drop across the given resistance and current through it. Applying Ohm’s law, the value of resistance can be determined.

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