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Question
In Wheatstone’s meter-bridge experiment, the null point is obtained in the middle one-third portion of the wire. Why is it recommended?
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Solution
- Due to the non-uniformity of the bridge wire and the development of contact resistance at the wire's ends, the value of unknown resistance X may not be accurate.
- To reduce these errors, the value of R is modified so that the null point is found in the middle one-third of the wire (between 34 and 66 cm), resulting in the smallest and virtually identical percentage errors in the measurement of lx and lR.
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