Measurement and Instrumentation
Potentiometer method of DC voltage measurement is more accurate than direct measurement using a voltmeter because

  It does not load the circuit at all.
 It loads the circuit to maximum extent.
 It uses centre zero galvanometer instead of voltmeter.
 It loads the circuit moderately.

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Measurement and Instrumentation
Assertion (A) : It is always desirable to take the reading of an indicating instrument very close to the full scale reading. Reason (R) : Accuracy of an indicating instrument is maximum at the full scale deflection and error increases as reading comes closer to the beginning of the scale.

 Both A and R are true but R is NOT the correct explanation of A
 A is true but R is false
 Both A and R are true and R is the correct explanation of A
 A is false bur R is true

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