Measurement and Instrumentation
A moving coil of a meter has 100 turns, and a length and depth of 10 mm and 20 mm respectively. It is positioned in a uniform radial flux density of 200 mT. The coil carries a current of 50 mA. The torque on the coil is

 1 µNm.
 100 µNm.
  200 µNm.
 2 µNm.

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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

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

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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

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

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