EC-302 Electronic Measurements and Instrumentation - Dec 2025 Question Paper

Under each question, How to answer lists the points an answer should cover, outlined by CampusPrep from the syllabus. Check the details against your textbook.

1. 7 Marks
   aDefine measurement. Explain static and dynamic errors in detail. Discuss the sources, types of errors, and their statistical analysis including mean, deviation, and standard deviation.
   How to answer

   • Define measurement as comparison with standard
   • Static errors vs dynamic errors characteristics
   • Sources and types: gross, systematic, random
   • Statistical analysis: mean, deviation, standard deviation with formulas
2. 7 Marks
   bDescribe the construction and working principle of DC and AC ammeters and voltmeters. Explain chopper type and solid-state AC voltmeters in detail.
   How to answer

   • PMMC based DC ammeter/voltmeter with shunt/multiplier
   • AC rectifier / electrodynamometer type for AC
   • Chopper type AC voltmeter block and operation
   • Solid-state AC voltmeter circuit and advantages
3. 7 Marks
   aWhat is instrument calibration? Explain the comparison method of calibration in detail. Discuss the importance and limitations of calibration.
   How to answer

   • Define calibration and need for traceability
   • Comparison method steps with standard instrument
   • Importance for accuracy and reliability
   • Limitations: standard accuracy, environment, cost
4. 7 Marks
   bExplain the construction and working of a Cathode Ray Oscilloscope (CRO) with a neat block diagram. Discuss its important applications.
   How to answer

   • CRT, electron gun, deflection and screen construction
   • Block diagram: vertical, horizontal, trigger, power
   • Working: deflection and synchronization
   • Applications: voltage, frequency, phase measurement
5. 7 Marks
   aExplain the working principle, balance conditions, and applications of Maxwell's bridge, Hay's bridge, and Schering bridge. Also explain impedance measurement using a Q-meter.
   How to answer

   • Bridge balance principle with impedance equation
   • Maxwell, Hay, Schering circuits and balance conditions
   • Applications for L and C measurement
   • Q-meter resonance method for impedance
6. 7 Marks
   bExplain the vertical and horizontal deflection systems and the time base circuit of a CRO. Discuss the importance and types of CRO probes.
   How to answer

   • Vertical system: attenuator, amplifier to Y-plates
   • Horizontal system and time base sawtooth generation
   • Synchronization and deflection sensitivity
   • Probe types: passive, active, current; importance of compensation
7. 7 Marks
   aExplain the construction, working principle, characteristics, advantages, and applications of Linear Variable Differential Transformer (LVDT).
   How to answer

   • Construction: primary, two secondaries, movable core
   • Working on differential mutual inductance
   • Characteristics: linearity, sensitivity, null position
   • Advantages and displacement applications
8. 7 Marks
   bExplain temperature transducers such as Resistance Temperature Detector (RTD), thermistor, and thermocouple. Compare their characteristics and applications.
   How to answer

   • RTD, thermistor, thermocouple principles
   • Construction and temperature-resistance/voltage relations
   • Comparison table of range, sensitivity, linearity
   • Selection for applications
9. 7 Marks
   aExplain the working principles of piezo-electric, optical, and photo-electric transducers. Discuss photo-emissive, photo-conductive, and photo-transistors.
   How to answer

   • Piezo-electric effect and charge generation
   • Optical and photo-electric conversion principles
   • Photo-emissive vs photo-conductive vs photo-transistor
   • Applications in measurement
10. 7 Marks
    bExplain the working principle and applications of signal generators. Describe sweep frequency generator and beat frequency oscillator in detail.
    How to answer

    • Signal generator block and functions
    • Sweep frequency generator operation
    • Beat frequency oscillator principle
    • Applications in testing and calibration
11. 7 Marks
    aExplain the construction and working principle of Liquid Crystal Display (LCD). Compare LED and LCD displays.
    How to answer

    • LCD construction: liquid crystal, polarizers, electrodes
    • Working on light polarization and field effect
    • LED vs LCD comparison on power, contrast, life
    • Applications of displays
12. 7 Marks
    bExplain the construction and working of pulse generators and square wave generators with suitable block diagrams.
    How to answer

    • Pulse generator blocks: trigger, width, repetition control
    • Square wave generator using multivibrator
    • Block diagrams with waveforms
    • Applications in digital testing
13. 7 Marks
    aExplain Digital-to-Analog Converters (DAC). Describe variable resistive type and R-2R ladder type DAC with circuit diagrams and working principles.
    How to answer

    • DAC definition and resolution concept
    • Variable resistive / weighted resistor DAC circuit
    • R-2R ladder network operation with currents
    • Comparison and applications
14. 7 Marks
    bExplain the construction and working principle of digital voltmeters and digital multimeters. Discuss resolution and sensitivity of digital multimeters.
    How to answer

    • Digital voltmeter block: ADC, display
    • Digital multimeter functions for V, I, R
    • Resolution as digits and counts
    • Sensitivity and input impedance discussion
15. 7 Marks
    aExplain integrating type ADC and voltage-to-frequency conversion technique. Discuss their advantages and limitations.
    How to answer

    • Integrating / dual-slope ADC operation phases
    • Voltage-to-frequency converter with integrator and pulse
    • Advantages: noise rejection, accuracy
    • Limitations: speed, complexity
16. 7 Marks
    bDiscuss the advantages of digital instruments over analog instruments. Compare their performance, accuracy, and applications.
    How to answer

    • Higher accuracy, resolution and no parallax
    • Performance comparison table
    • Accuracy, speed, input impedance points
    • Applications in automation and logging