# Electronic Instrumentation and Measurements KEC-057 Aktu Btech Short Question Pdf

Discover Electronic Instrumentation and Measurements Short Question Notes from the B.Tech., AKTU Quantum Book. Investigate measurement theories, instrumentation methods, and the uses of each for accurate data collection and interpretation.

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## Unit-I: Electrical Measurements (Short Question)

Q1. Define measurement.

Ans. Measurement is the process by which one can convert physical parameters to meaningful numbers.

Q2. Define accuracy and precision with suitable examples.

OR

Explain accuracy and precision.

Ans. A. Accuracy:

• 1. The degree to which a measured value is accurate in relation to a reference or known value.
• 2. For example, if you obtain a weight measurement of 3.2 kg for a given substance, but the actual or known weight is 10 kg, then your measurement is not accurate. in this case, your measurement is not close to the known value.

B. Precision:

• 1. The proximity of two or more measurements to one another is referred to as precision.
• 2. Using the example above, if you weight a given substance five times, and get 3.2 kg each time, then your measurement is very precise.

Q3. What are the applications of measuring system?

Ans. 1. Monitoring of processes and operations.

2. Control of processes and operations.

3. Experimental engineering analysis.

Q4. Give the sources of error in measurement.

Ans.

• 1. Insufficient knowledge of operation.
• 2. Poor maintenance.
• 3. Change in process parameters.
• 4. Manufacturing defect.
• 5. Loading effect in instruments.

Q5. Define random error and gross error with suitable example.

OR

Explain random error and gross error.

Ans. A. Random error: There are some errors that are eliminated or at least accounted for that are caused by systematic and instrumental errors. As there are no known causes for such errors, they are referred to as random errors.

Example: Measurement of current through ammeter in ideal as well as actual environment, the error in the ratings is observed.

B. Gross error: The human being’s negligence or lack of experience is primarily to blame for the big blunder. They include errors made by people when reading, recording, and computing results. These mistakes were also brought on by a misaligned instrument.

Example: Misreading of an instrument.

Q6. Compare analog instruments with digital instruments.

Ans.

Q7. Name the different types of systematic errors.

Ans. 1. Instrumental error.

2. Environmental error.

3. Observational error.

Q8. The measured value of a resistance is 10.25 Ω, whereas its value is 10.22 Ω. Determine the absolute error of measurement.

Ans. Given: Measured value of resistance = 10.25 Ω,

True value = 10.22 Ω

To Find: Absolute error.

Absolute error = Measured value – true value

Q9. Explain true value.

Ans. The value that would result from a flawless measurement is the measurement’s true value.

Q10. Define primary and secondary standards.

Ans. A. Primary standard:

• 1. A primary standard is one that is exact enough to stand alone and not be calibrated by or compared to other standards.
• 2. Secondary standards are specified in terms of other dimensions including time, mass, and length. Other standards referred to as working standards are calibrated using primary standards.

B. Secondary standard:

• 1. A standard created in the lab for a particular analysis is referred to as a secondary standard.
• 2. It is frequently standardized using a fundamental standard.

## Unit-II: Electronic Instruments (Short Question)

Q1. How emitter-follower structure reduces voltmeter loading effect?

Ans. When driving current through a deflection meter’s coil, an emitter-follower delivers a high input resistance to the voltage being measured and a low output resistance. Hence, utilizing emitter-follower considerably reduces voltmeter loading.

Q2. Define the term floating.

Ans. The common terminal of the power supply is grounded in electronic voltmeter circuits. The voltmeters’ supply voltages are referred to as floating if these circuits are not grounded at any point. This implies that every terminal to which the common terminal may be connected will have the same absolute voltage.

Q3. Name the different types of multimeter probes used.

Ans. 1. High voltage probe

2. High current probe

3. RF probe

Q4.  What is the main function of RF probe ?

Ans. The primary job of an RF probe is to rectify the RF waveform into a DC voltage that is equal to its maximum level.

Q5. List the uses of probe.

Ans. 1. To lower the voltage to a level that can be measured, a high-voltage probe uses a resistive divider.

2. To lower an AC current to a level that can be measured, a high-current probe uses the current transform.

Q6. Define zero-crossing detector.

Ans. When the integrator output waveform is negative, the zero-crossing detector, a voltage comparator, produces a high output; when the positive going ramp ends, the output is low.

Q7. Name the different types of DVM.

Ans.

• 1. Ramp-type DVM.
• 2. Dual-slope type DVM.
• 3. Integrating type DVM.
• 4. Successive approximation DVM.

Q8. What are the advantages of DVM?

Ans.

• 1. High accuracy and resolution.
• 2. Greater speed.
• 3. No parallel error.
• 4. Reduced human error.

Q9. Write the differences between digital and analog meters.

Ans.

• 1. Digital meters have high speed as compared to analog meters.
• 2. Digital meters can be programmed while analog meters cannot be programmed.
• 3. Digital meters have automatic range selection while analog meters have not.
• 4. Accuracy of digital meter is better than analog meters.

Q10. What do you understand by instrument calibration?

OR

Explain instrument calibration.

Ans. Instrument calibration is the process of comparing the measured values produced by an instrument to the standard measured values in order to assess its accuracy.

Q11. Explain multimeter.

Ans. An equipment called a multimeter is used to measure electrical current, voltage, and typically resistance over a wide range of values.

## Unit-III: Measuring Methods (Short Question)

Q1.What do you understand by low, medium and high resistances?

Ans. i. Low resistance : All the resistance of the order of 1 Ω and under may be classified as low resistance.

ii. Medium resistance : This class includes resistance from 1Ω upwards to about 0.1 MΩ.

iii. High resistance : Resistance of the order of 0.1 MΩ and upwards are classified as high resistance.

Q2. Write the mathematical equation for unknown resistance of Kelvin bridge.

Ans. The value of unknown resistance Q is:

Q3. What is Megger ?

Ans. Meggers (or megohmmeters) are devices that gauge how resistant electrical circuits’ insulation is to the ground and to one another. An emf source and a voltmeter make up a megger.

Q4. What is the sensitivity of Wheatstone’s bridge ? Explain briefly.

Ans.  The galvanometer’s current is zero when the bridge is balanced. Yet, when there is an imbalance, current flows through the galvanometer and causes a deflection. The sensitivity of the galvanometer determines the degree of deflection.

Q5. Give the applications of Wheatstone bridge.

Ans. i To measure the resistance in the range of 1 Ω to few megaohm.

ii. To measure the DC resistance of various type of wires.

iii. To locate the cable faults in a telephone line.

Q6. What is quality factor and its importance in measurement?

Ans. The quality factor or Q factor of the inductor is the ratio of the inductive reactance and resistance at the operating frequency.

The power dissipation of an inductor can be used to define its quality. For the least amount of power dissipation, an inductor should have maximum quality and zero resistance.

Q7. What do you mean by dissipation factor ? Explain.

Ans. The dissipation factor (D) defines the quality of the capacitor. A lossy capacitor, which has relatively low resistance, dissipates some power.

Q8. Define importance of Kelvin’s double bridge over Wheatstone bridge.

Ans. 1. The twin bridge proposed by Kelvin is more precise than the Wheatstone bridge.

2. The influence of the load and the contact resistance is totally eliminated.

Q9. Write the mathematical equation for unknown resistance of Wheatstone bridge.

Ans. The value of unknown resistance R is:

Q10. Write mathematical term of AC bridge.

Ans.

## Unit-IV: Electronic Measurements (Short Question)

Q1. Write the applications of spectrum analyzer.

Ans.

• i. Amplitude modulation.
• ii. Frequency modulation.
• iii. Pulse-width and repetition mode measurements
• iv. Tuning an amplifier.
• v. RF interference.

Q2. Explain the various applications of CRO in measurement.

Ans.

• i. Measurement of voltage
• ii. Measurement of current
• iii. Measurement of frequency
• iv. Measurement of displacement

Q3. What is a CRO ?

Ans. A extremely helpful and adaptable laboratory tool, the cathode ray oscilloscope is used to show, measure, and analyze waveforms and other phenomena in electrical and electronic circuits.

Q4. Define display devices.

Ans. Displays serve as the final stage of an instrument since they are the interface between it and the human observer.

Q5. What are the essential components of a CRT?

Ans. i Electron gun

ii. Electro beam deflector

iii. Screen and phosphors.

Q6. Why triggering is needed in CRO?

Ans. In order to synchronize the sweep frequency and point signal, the incoming signal is converted into a trigger pulse using a trigger circuit.

Q7. Explain rise time and fall time with neat diagram.

OR

Explain rise time and fall time.

Ans. Rise time: The rise time, (tr) is defined as the time for the output to reach from 10 % to the 90 % of the amplitude.

Fall time: The fall time (tf) is the time for the output to go for 90 % to 10 % of the amplitude.

Q8. What is the function of digital storage oscilloscope?

Ans.  The waveform is sampled at regular intervals and each sample is transformed to digital form using an analogue to digital converter in a digital storage oscilloscope (DSO) (ADC).

Q9. What is the function of electron lens ?

Ans. The electron lens’s job is to concentrate the electrons onto a tiny point on the tube’s screen.

Q10. What do you mean by pulse distortion ?

Ans. In pulse distortion, the coupling capacitor imposes high or low frequency distortion at the top and bottom of the waveform if the pulse waveform is AC linked. When an instrument’s input capacitance creates rise time and fall time that aren’t present in the original pulse, the waveform of the pulse is high frequency distorted.

## Unit-V: Instrumentation (Short Question)

Q1. Explain transducers and inverse transducers.

Ans. A. Transducers : A transducer is a device that changes an electrical quantity from a non-electrical one.

B. Inverse transducer : A device that changes an electrical quantity into a non-electrical quantity is known as an inverse transducer.

Q2. What are the various advantages of transducers ?

Ans. 1. Electrical amplification and attenuation can be done easily.

2. No moving mechanical parts.

3. Very small electric power required.

Q3. Give the various disadvantages of transducers.

Ans. 1. Design is complicated.

2. The electrical transducer is sometimes less reliable than mechanical type.

Q4. What are the applications of transducers in various fields?

Ans. 1. Electromagnetic:

a. Antennas                                         b. Hall-effect sensors

c. Disk read and write heads               d. Magnetic cartridges.

2. Electromechanical:

a. Accelerometers                                b. Pressure sensors

c. Galvanometers                                 d. LVDT

e. Load cells                                         f. Potentiometers.

Q5. Give the factors affecting choice of transducers.

Ans.

• i. Operating principle.
• ii. Sensitivity.
• iii. Operating range.
• iv. Accuracy.
• v. Cross sensitivity.

Q6. What are strain gauges ?

Ans. In experimental stress analysis, it is used to measure strain and related stress. It operates according to the piezoresistive effect.

Q7. Define LVDT.

Ans.  Linear Variable Differential Transformer is referred to as LVDT. It is a transducer of the inductive variety that converts linear motion into electrical impulses.

Q8. Give the advantages of LVDT.

Ans.

• i. High range.
• ii. Friction and electrical isolation.
• iii. High output and high sensitivity.
• iv. Low hysteresis.
• v. Low power consumption.
• vi. Ruggedness.

Q9. Write the disadvantages of LVDT.

Ans. 1. Vibrations have an impact on the performance of transducers.

2. The transducer’s performance is impacted by temperature.

3. Dynamic response is limited.

Q10. Give the advantages of capacitive transducers.

Ans. i. They are extremely sensitive.

ii. They respond to frequencies well.

iii. Capacitive transducers have relatively low force needs.

Q11. Write the disadvantages of capacitive transducers.

Ans. 1. The instrumentation circuitry that these transducers are employed with is extremely complicated.

2. The measurement is affected in a non-linear way by the edge effect.

Q12. What are the applications of thermistors?

Ans.

• 1. To keep an eye on the engine’s coolant and/or oil temperatures.
• 2. To keep an incubator’s temperature under observation.
• 3. To keep track of the battery packs’ charging-related temperature.
• 4. To keep an eye on the 3D printers’ hot ends’ temperature.

Q13. Explain bender and twister.

Ans. “Benders” or “twisters” can be created by joining two crystals so that their electrical axes are perpendicular. This indicates that bending a bender results in an output voltage. A twister motion applied to a twister results in an output, too.