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Chapter 21: Q28CQ (page 773)

Why can a null measurement be more accurate than one using standard voltmeters and ammeters? What factors limit the accuracy of null measurements?

Short Answer

Expert verified

Standard devices alter the circuit during the measurement whereas the null measurements do not alter it. Thus, null measurements are more accurate.

Step by step solution

01

Null measurements

To avoid any alteration of the circuit by the measuring device, while taking the measurement, null measurements are used. In these measurements, the voltage is balanced such that no current can flow through the measuring device. Thus, no alteration of the circuit will take place.

02

Explanation of the factors which limit the accuracy of null measurements

Measuring devices such as voltmeters and ammeters alter the circuit during the measurement. This results in inaccurate values. In null measurements, voltage is balanced, such that the current flowing through the measuring device is zero. Thus, no alteration of the circuit will take place and the measurements will be more accurate.

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