27 real Measurements & Instrumentation questions from the ECE Core bank, as asked in Indian campus drives and tech interviews. Every question has a verified answer and an AI-tutor explanation on placd — free to start.
1. What is Strain gauge?
Junior
A.resolution is the smallest change an instrument can display, accuracy is closeness to the true value; a 6½-digit meter can still be inaccurate if uncalibrated
B.bonded metal foil whose resistance changes with strain, gauge factor about 2, read in a Wheatstone bridge with a dummy gauge for temperature compensation
C.reduction of the measured voltage because the meter's finite input resistance draws current, which is why DMMs use 10 MΩ inputs and analogue meters quote Ω/V sensitivity
D.displacement transducer with a movable core between a primary and two secondaries, giving a null at centre and a phase reversal through it, with no friction or wear
2. Which term means: "bonded metal foil whose resistance changes with strain, gauge factor about 2, read in a Wheatstone bridge with a dummy gauge for temperature compensation"?
A.Strain gauge — displacement transducer with a movable core between a primary and two secondaries, giving a null at centre and a phase reversal through it, with no friction or wear
B.Strain gauge — integrating voltmeter that ramps up on the input for a fixed time then down on the reference, rejecting mains hum when the integration period is a multiple of 20 ms
C.Strain gauge — two dissimilar metals producing a Seebeck voltage at their junction, about 41 µV/°C for type K, requiring cold-junction compensation
D.Strain gauge — bonded metal foil whose resistance changes with strain, gauge factor about 2, read in a Wheatstone bridge with a dummy gauge for temperature compensation
A.two dissimilar metals producing a Seebeck voltage at their junction, about 41 µV/°C for type K, requiring cold-junction compensation
B.bonded metal foil whose resistance changes with strain, gauge factor about 2, read in a Wheatstone bridge with a dummy gauge for temperature compensation
C.reduction of the measured voltage because the meter's finite input resistance draws current, which is why DMMs use 10 MΩ inputs and analogue meters quote Ω/V sensitivity
D.resolution is the smallest change an instrument can display, accuracy is closeness to the true value; a 6½-digit meter can still be inaccurate if uncalibrated
5. Which term means: "two dissimilar metals producing a Seebeck voltage at their junction, about 41 µV/°C for type K, requiring cold-junction compensation"?
A.Thermocouple — bonded metal foil whose resistance changes with strain, gauge factor about 2, read in a Wheatstone bridge with a dummy gauge for temperature compensation
B.Thermocouple — two dissimilar metals producing a Seebeck voltage at their junction, about 41 µV/°C for type K, requiring cold-junction compensation
C.Thermocouple — displacement transducer with a movable core between a primary and two secondaries, giving a null at centre and a phase reversal through it, with no friction or wear
D.Thermocouple — quartz or PZT element generating charge proportional to applied force, suitable only for dynamic measurements and read through a charge amplifier
A.displacement transducer with a movable core between a primary and two secondaries, giving a null at centre and a phase reversal through it, with no friction or wear
B.two dissimilar metals producing a Seebeck voltage at their junction, about 41 µV/°C for type K, requiring cold-junction compensation
C.reduction of the measured voltage because the meter's finite input resistance draws current, which is why DMMs use 10 MΩ inputs and analogue meters quote Ω/V sensitivity
D.quartz or PZT element generating charge proportional to applied force, suitable only for dynamic measurements and read through a charge amplifier
8. Which term means: "displacement transducer with a movable core between a primary and two secondaries, giving a null at centre and a phase reversal through it, with no friction or wear"?
A.LVDT — displacement transducer with a movable core between a primary and two secondaries, giving a null at centre and a phase reversal through it, with no friction or wear
B.LVDT — two dissimilar metals producing a Seebeck voltage at their junction, about 41 µV/°C for type K, requiring cold-junction compensation
C.LVDT — resolution is the smallest change an instrument can display, accuracy is closeness to the true value; a 6½-digit meter can still be inaccurate if uncalibrated
D.LVDT — spectrum analyser IF filter width that sets the ability to separate close tones; reducing it tenfold lowers the displayed noise floor 10 dB but slows the sweep
A.reduction of the measured voltage because the meter's finite input resistance draws current, which is why DMMs use 10 MΩ inputs and analogue meters quote Ω/V sensitivity
B.figure traced on an oscilloscope in X-Y mode by two sinusoids, whose tangency counts give the frequency ratio and whose ellipse shape gives phase difference
C.bonded metal foil whose resistance changes with strain, gauge factor about 2, read in a Wheatstone bridge with a dummy gauge for temperature compensation
D.integrating voltmeter that ramps up on the input for a fixed time then down on the reference, rejecting mains hum when the integration period is a multiple of 20 ms
11. Which term means: "figure traced on an oscilloscope in X-Y mode by two sinusoids, whose tangency counts give the frequency ratio and whose ellipse shape gives phase difference"?
A.Lissajous pattern — two dissimilar metals producing a Seebeck voltage at their junction, about 41 µV/°C for type K, requiring cold-junction compensation
B.Lissajous pattern — figure traced on an oscilloscope in X-Y mode by two sinusoids, whose tangency counts give the frequency ratio and whose ellipse shape gives phase difference
C.Lissajous pattern — resolution is the smallest change an instrument can display, accuracy is closeness to the true value; a 6½-digit meter can still be inaccurate if uncalibrated
D.Lissajous pattern — reduction of the measured voltage because the meter's finite input resistance draws current, which is why DMMs use 10 MΩ inputs and analogue meters quote Ω/V sensitivity
A.figure traced on an oscilloscope in X-Y mode by two sinusoids, whose tangency counts give the frequency ratio and whose ellipse shape gives phase difference
B.integrating voltmeter that ramps up on the input for a fixed time then down on the reference, rejecting mains hum when the integration period is a multiple of 20 ms
C.spectrum analyser IF filter width that sets the ability to separate close tones; reducing it tenfold lowers the displayed noise floor 10 dB but slows the sweep
D.quartz or PZT element generating charge proportional to applied force, suitable only for dynamic measurements and read through a charge amplifier
14. Which term means: "integrating voltmeter that ramps up on the input for a fixed time then down on the reference, rejecting mains hum when the integration period is a multiple of 20 ms"?
A.Dual-slope DVM — displacement transducer with a movable core between a primary and two secondaries, giving a null at centre and a phase reversal through it, with no friction or wear
B.Dual-slope DVM — bonded metal foil whose resistance changes with strain, gauge factor about 2, read in a Wheatstone bridge with a dummy gauge for temperature compensation
C.Dual-slope DVM — integrating voltmeter that ramps up on the input for a fixed time then down on the reference, rejecting mains hum when the integration period is a multiple of 20 ms
D.Dual-slope DVM — spectrum analyser IF filter width that sets the ability to separate close tones; reducing it tenfold lowers the displayed noise floor 10 dB but slows the sweep
A.reduction of the measured voltage because the meter's finite input resistance draws current, which is why DMMs use 10 MΩ inputs and analogue meters quote Ω/V sensitivity
B.figure traced on an oscilloscope in X-Y mode by two sinusoids, whose tangency counts give the frequency ratio and whose ellipse shape gives phase difference
C.quartz or PZT element generating charge proportional to applied force, suitable only for dynamic measurements and read through a charge amplifier
D.resolution is the smallest change an instrument can display, accuracy is closeness to the true value; a 6½-digit meter can still be inaccurate if uncalibrated
17. Which term means: "reduction of the measured voltage because the meter's finite input resistance draws current, which is why DMMs use 10 MΩ inputs and analogue meters quote Ω/V sensitivity"?
A.Loading effect — two dissimilar metals producing a Seebeck voltage at their junction, about 41 µV/°C for type K, requiring cold-junction compensation
B.Loading effect — integrating voltmeter that ramps up on the input for a fixed time then down on the reference, rejecting mains hum when the integration period is a multiple of 20 ms
C.Loading effect — resolution is the smallest change an instrument can display, accuracy is closeness to the true value; a 6½-digit meter can still be inaccurate if uncalibrated
D.Loading effect — reduction of the measured voltage because the meter's finite input resistance draws current, which is why DMMs use 10 MΩ inputs and analogue meters quote Ω/V sensitivity
A.displacement transducer with a movable core between a primary and two secondaries, giving a null at centre and a phase reversal through it, with no friction or wear
B.quartz or PZT element generating charge proportional to applied force, suitable only for dynamic measurements and read through a charge amplifier
C.reduction of the measured voltage because the meter's finite input resistance draws current, which is why DMMs use 10 MΩ inputs and analogue meters quote Ω/V sensitivity
D.figure traced on an oscilloscope in X-Y mode by two sinusoids, whose tangency counts give the frequency ratio and whose ellipse shape gives phase difference
20. Which term means: "quartz or PZT element generating charge proportional to applied force, suitable only for dynamic measurements and read through a charge amplifier"?
A.Piezoelectric transducer — figure traced on an oscilloscope in X-Y mode by two sinusoids, whose tangency counts give the frequency ratio and whose ellipse shape gives phase difference
B.Piezoelectric transducer — bonded metal foil whose resistance changes with strain, gauge factor about 2, read in a Wheatstone bridge with a dummy gauge for temperature compensation
C.Piezoelectric transducer — displacement transducer with a movable core between a primary and two secondaries, giving a null at centre and a phase reversal through it, with no friction or wear
D.Piezoelectric transducer — quartz or PZT element generating charge proportional to applied force, suitable only for dynamic measurements and read through a charge amplifier
A.resolution is the smallest change an instrument can display, accuracy is closeness to the true value; a 6½-digit meter can still be inaccurate if uncalibrated
B.figure traced on an oscilloscope in X-Y mode by two sinusoids, whose tangency counts give the frequency ratio and whose ellipse shape gives phase difference
C.quartz or PZT element generating charge proportional to applied force, suitable only for dynamic measurements and read through a charge amplifier
D.displacement transducer with a movable core between a primary and two secondaries, giving a null at centre and a phase reversal through it, with no friction or wear
23. Which term means: "resolution is the smallest change an instrument can display, accuracy is closeness to the true value; a 6½-digit meter can still be inaccurate if uncalibrated"?
A.Resolution versus accuracy — resolution is the smallest change an instrument can display, accuracy is closeness to the true value; a 6½-digit meter can still be inaccurate if uncalibrated
B.Resolution versus accuracy — quartz or PZT element generating charge proportional to applied force, suitable only for dynamic measurements and read through a charge amplifier
C.Resolution versus accuracy — figure traced on an oscilloscope in X-Y mode by two sinusoids, whose tangency counts give the frequency ratio and whose ellipse shape gives phase difference
D.Resolution versus accuracy — reduction of the measured voltage because the meter's finite input resistance draws current, which is why DMMs use 10 MΩ inputs and analogue meters quote Ω/V sensitivity
A.spectrum analyser IF filter width that sets the ability to separate close tones; reducing it tenfold lowers the displayed noise floor 10 dB but slows the sweep
B.displacement transducer with a movable core between a primary and two secondaries, giving a null at centre and a phase reversal through it, with no friction or wear
C.reduction of the measured voltage because the meter's finite input resistance draws current, which is why DMMs use 10 MΩ inputs and analogue meters quote Ω/V sensitivity
D.bonded metal foil whose resistance changes with strain, gauge factor about 2, read in a Wheatstone bridge with a dummy gauge for temperature compensation
26. Which term means: "spectrum analyser IF filter width that sets the ability to separate close tones; reducing it tenfold lowers the displayed noise floor 10 dB but slows the sweep"?
A.Resolution bandwidth — integrating voltmeter that ramps up on the input for a fixed time then down on the reference, rejecting mains hum when the integration period is a multiple of 20 ms
B.Resolution bandwidth — spectrum analyser IF filter width that sets the ability to separate close tones; reducing it tenfold lowers the displayed noise floor 10 dB but slows the sweep
C.Resolution bandwidth — quartz or PZT element generating charge proportional to applied force, suitable only for dynamic measurements and read through a charge amplifier
D.Resolution bandwidth — two dissimilar metals producing a Seebeck voltage at their junction, about 41 µV/°C for type K, requiring cold-junction compensation
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