ECE :: Measurements and Instrumentation
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In a single phase power factor meter the phase difference between currents in the two pressure coils is
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In an ac coordinate potentiometer, the currents inphase and quadrature potentiometer are adjusted to be
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Both X and Y plates of a CRO are excited by ac signals. The display is an ellipse which makes one rotation in 5 seconds. This means that
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In order to achieve accuracy, the slide wire of a potentiometer should be
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In measuring resistance using voltmeter and ammeter, the resistances of voltmeter and ammeter also affect the accuracy of measurement.
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The difference between measured value and true value is called
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In air friction damping
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For measuring a very high resistance we should use
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Assertion (A): Damping in a vibration galvanometer is small.
Reason (R): Vibration galvanometer is a PMMC instrument.
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A.
the air pressure opposes the motion of piston when it is moving inwards
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B.
the air pressure opposes the motion of piston when it is moving outwards
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C.
the air pressure opposes the motion of piston both when it is moving inwards as well as outwards
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D.
the air pressure may oppose or aid the motion of piston depending on the design
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