Measurement and Instrumentation
Which of the following devices should be used for accurate measurement of low D.C. voltage?

C. potentiometer
Small range thermocouple voltmeter
Small range moving coil voltmeter
None of these

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Measurement and Instrumentation
In DC potentiometer measurments, a second reading is often taken after reversing the polarities of the DC supply and the unknown voltage and the average of the two reading is taken. This is with a view of eliminate the effects of

 Ripples of the DC supply.
 Errorneous standardisation.
  Stray thermal emfs.
 Stray magnetic fields.

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