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 does not load the circuit at all.
 It uses centre zero galvanometer instead of voltmeter.

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Measurement and Instrumentation
Assertion(A): A low power factor wattmeter has special constructional features to ensure accurate measurment. Reason(R): Extension of wattmeter range in DC circuit can be easily done by using current and potential transformer

 Both A and R is true and R is not correct explanation of A.
 A is false R is true.
 A is true R is false.
 Both A and R is true and R is correct explanation of A C.

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