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

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

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Measurement and Instrumentation
Assertion (A) : Precision is a necessary prerequisiteof accuracy. Reason (R) : Precision guarantees accuracy.

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

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