In order to achieve accuracy, the slide wire of a potentiometer should be
Assertion (A): CRO can be used to study waveshape accurately.
Reason (R): Input impedance of a CRO is very high.
Two wattmeter method for 3 phase power measurement can be used only for
The advantage of LVDT over inductive bridge type transducer is that
Acoustic strain gauges
A CT is used to feed current coils of wattmeter, energy meter, power factor meter and an ammeter. Then
In measurements using strain gauge, the dummy strain gauge is used to
Which one of the following is true?
An oscilloscope has an input impedance consisting of 1 MΩ andpF is parallel. A high impedance probe connected to input of this oscilloscope has aMΩ series resistance. ThisMΩ series resistance
Assertion (A): Damping in a vibration galvanometer is small.
Reason (R): Vibration galvanometer is a PMMC instrument.
Four capacitors are in parallel. Their values are 36.3 μF, 3.μF, 34.μF andμF with an uncertainty of digit in the last place. The total capacitance in significant figures is
In measuring resistance using voltmeter and ammeter, the resistances of voltmeter and ammeter also affect the accuracy of measurement.
LVDT is used to measure
The scale of PMMC instrument is linear.
A coil resonates at 1 MHz with a resonating capacitance ofpF. AtpF, resonance is obtained with a resonating capacitor ofpF. The self capacitance of coil is
In a Weston synchronoscope the deflecting torque is zero when
In an ac single phase energy meter, the potential coil is put on
The accuracy of a multimeter is about
Crompton potentiometer has
In a CRO the Y plates are oriented
To measure moisture in wood, the most suitable method is
A Weston frequency meter is
Which of the following combinations is not used in thermocouple transducer measurement of temperature?
The dynamic characteristics of capacitive transducer are similar to those of
Which of the following is used as detector in audio frequency ac bridges?
Assertion (A): The gall tinsley potentiometer is a coordinate potentiometer and has two exactly similar potentiometers.
Reason (R): An ac potentiometer may measure the unknown voltage in polar form or rectangular coordinate form.
Assertion (A): Thermistors are commonly used to measure hot spot temperatures in electric machines.
Reason (R): Thermistor has the advantages of high temperature coefficient, small size and high speed of response.
A peak responding ac voltmeter using a half wave rectifier has been calibrated to read 1 V for 1 V rms sine wave input. If input is 1 V dc the reading will be
Assertion (A): Megger is used to check insulation resistance of cables.
Reason (R): Insulation resistance of cables is very high.
The chemical effect of current is used in
The output of a Piezoelectric crystal has
Induction wattmeter is an absolute instrument.
In a current transformers
Assertion (A): For best results the system of a D'Arsonval galvanometer should be slightly under damped.
Reason (R): Degree of damping affects the time taken by the instrument to come to final position.
The accuracy of an instrument is determined by
If σ standard deviation, probable error
An E transformer is a
TheMHz in the specification of CRO means that
Rayleigh current balance is an absolute instrument.
The electrical power to a megger is provided by
DC voltage of the order of a few mV can be accurately of measured by
Absolute instruments are used in
For measuring inductance with high Q, we should use
A resistance strain gauge has a resistance of about
Assertion (A): A power factor meter operates on dynamometer principle.
Reason (R): A power factor meter does not have a control spring.
The pressure coil of a wattmeter should be connected to the supply side of the current coil when
In a vibrating reed frequency meter the natural frequency of two adjacent reeds have a difference of
The time base of a high frequency CRO whose screen diameter iscm is set atμ sec/cm. The lowest frequency which can be fully displayed on the screen is
Eddy currents are essential for the deflecting torque of an induction wattmeter.
The torque in induction wattmeters due to
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