(SEM III) THEORY EXAMINATION 2022-23 SENSOR AND INSTRUMENTATION

This question paper is designed for students studying Sensors & Transducers / Measurement Systems / Virtual Instrumentation—common subjects in Electronics Engineering, Instrumentation Engineering, Mechatronics, Automation, Robotics, and Electrical Engineering.
The paper tests both conceptual knowledge and analytical problem-solving skills, ensuring students understand how real-world measurement systems and smart sensing technologies work.

The exam is divided into three sections: A, B, and C, with a total of 70 marks. It covers:

Working principles of sensors and transducers

Signal conditioning

Virtual instrumentation

Digital & analog converters

Smart sensors and Industry 4.0 applications

Data acquisition systems

Temperature, displacement, strain, pressure measurement

Sensor characteristics, selection criteria and practical design

SECTION A — Short Conceptual Questions (20 Marks)

This section contains 10 short questions, testing the student's basic understanding of sensors, programming elements, and smart instrumentation.

Topics include:

Characteristics of sensors (sensitivity, linearity, range, resolution, drift, etc.)

Factors for selecting transducers (accuracy, cost, environment, frequency response, etc.)

Thermocouple vs. Thermistor (construction, working principle, temperature range, sensitivity)

RTD materials like platinum, nickel, copper and their temperature ranges

Syntax of WHILE loops in programming environments like LabVIEW or C

Formula Node (commonly used in LabVIEW for quick math operations)

Difference between counter & timer (counting pulses vs measuring time intervals)

Data Sockets for network data exchange

Features of smart sensors (self-calibration, self-diagnosis, interfacing capabilities)

Smart sensors used in industrial robots (position sensing, torque sensing, vision sensing)

This section tests fundamental recall, definitions, and conceptual clarity.

SECTION B — Descriptive and Analytical Questions (30 Marks)

Students must attempt any three questions.
These questions require diagrams, mathematical explanation, working principles, and comparative analysis.

The section covers mid-level concepts including:

1. LVDT (Linear Variable Differential Transformer)

Construction (primary & two secondary windings, movable ferromagnetic core)

Working (differential voltage as displacement changes)

Advantages (high resolution, frictionless) and disadvantages

2. Thermocouple Construction & Numerical Problem

Working principle based on Seebeck effect

Chromel-Alumel thermocouple behavior

Given emf, coil resistance, full-scale current, lead resistance

Students must compute required series resistance

Includes temperature coefficient of resistance-based calculation
This checks the student’s analytical and numerical solving ability.

3. Virtual Instrumentation vs Conventional Instruments

Covers LabVIEW-based virtual systems, modularity, programmability, flexibility, and comparison with hardware-only tools.

4. DAC Methods (R-2R Ladder & Weighted Resistors)

Explains binary-to-analog conversion, switching networks, accuracy, advantages/disadvantages.

5. Architecture of Smart Sensors

Discusses microcontroller/microprocessor integration, memory, ADC, conditioning circuits, communication interface, signal processing blocks.

This section evaluates a student’s ability to explain working principles, derive formulas, interpret circuits, and apply concepts to real measurement systems.

SECTION C — Advanced Application-Oriented Questions (20 Marks)

Students choose one part from each question.
This section tests deep technical understanding, design approaches, problem solving, and modern sensing technologies.

Q3: Strain Measurement OR Piezoelectric Sensors

Part (a):

Working of strain gauge (change in resistance with deformation)

Strain gauge characteristics (gauge factor, hysteresis, linearity, sensitivity)

Part (b):

Piezoelectric effect with diagram

Crystal generating voltage under pressure

Numerical: given thickness, sensitivity, pressure → calculate voltage

Calculate charge sensitivity using permittivity

This question tests instrumentation mathematics + sensor physics.

Q4: Hall Effect Sensors OR Capacitive Level Sensors

Part (a):

Definition of Hall effect

Measuring fluid level using magnetic field & Hall sensors

Part (b):

Working of capacitive level sensors

Advantages & disadvantages

Applications (chemical plants, food industry, oil tanks)

This evaluates knowledge of electromagnetic and capacitive sensing.

Q5: Data Structures OR Virtual Instrumentation Hardware/Software

Part (a):

Explanation of different programming structures (sequential, conditional, looping)

Part (b):

Role of hardware components (DAQ cards, sensors, signal conditioning modules)

Role of software (LabVIEW, MATLAB)

Q6: Data Acquisition System (DAS) OR Successive Approximation ADC

Part (a):

Complete block diagram of DAS                         Explanation of:

Sensors                                                                Signal conditioning

Multiplexers                                                         ADC

Processing unit                                                    Display unit

Part (b):

Working of Successive Approximation ADC        SAR register

Comparator-based binary searching                   Applications of ADC in industry & instrumentation

Q7: Smart Sensor Characteristics OR Applications in Smart Cities

Part (a):

Detailed discussion on self-calibration, multi-sensing, communication, self-diagnosis

Part (b):

Smart city applications:                     Traffic management

Pollution monitoring                         Water quality tracking

Smart lighting                                    Waste management

This section tests understanding of advanced IoT, automation, and Industry 4.0 concepts.

OVERALL PURPOSE OF THE PAPER

This exam evaluates the student’s capability to:

Understand the physics, construction & working of sensors

Analyze measurement circuits using real data

Explain the difference between traditional & virtual instrumentation

Work with DACs, ADCs, Smart Sensors, and Data Acquisition

Interpret sensor characteristics and select correct sensors for applications

Apply instrumentation principles to industrial and automation problems

Connect theory with practical applications in robotics, smart cities, and process industries

It is a balanced assessment of both theoretical knowledge and practical instrumentation skills needed in modern electronics and automation fields.