(SEM IV) THEORY EXAMINATION 2023-24 SENSOR & INSTRUMENTATION

This document is a B.Tech (Semester IV) Theory Examination Question Paper for the subject BOE405 – Sensor & Instrumentation, conducted in the academic year 2023–2024.
It is a 3-hour, 70-mark examination designed to assess students’ understanding of sensors, transducers, instrumentation systems, virtual instrumentation, DAC/ADC principles, strain gauges, ultrasonic sensors, Hall-effect devices, data acquisition systems, smart sensors, and graphical programming.

SECTION A – Short Answer Questions (14 Marks)

Seven 2-mark questions test fundamental concepts:

Definition of sensors and transducers            Criteria for selecting a sensor for a specific application

Definition of a thermistor                                  Advantages of virtual instrumentation

Purpose of counters in data acquisition systems    Use of data sockets in network communication

Definition and meaning of smart sensors

This section checks basic terminology and foundational knowledge in instrumentation.

SECTION B – Descriptive / Numerical / Diagrammatic Questions (21 Marks)

Students must attempt any three of the following:

a. Optical Encoder for Displacement Measurement

Explains how shaft rotation is converted into digital pulses through light interruption.

b. RTD Working + Numerical Problem

The question includes:

Working of Resistance Temperature Detector (RTD)

Given:

R₀ = 100 Ω at 0°C

Temperature coefficient (α) = 0.385 Ω/°C

Compute resistance at 100°C using:

• RT=R0(1+αT)R_T = R_0 (1 + \alpha T)RT​=R0​(1+αT)

c. Graphical Programming in Virtual Instrumentation

Description of block-diagram-based programming (LabVIEW style), loops, functions, front panel, and data flow.

d. Weighted Resistor DAC

Explains DAC working and asks to calculate output voltage for binary code 1011.

e. Application of Smart Sensors in Robot Control

Discusses feedback, adaptive control, self-calibration, and real-time monitoring in robotics.

SECTION C – Long Answer / Analytical Instrumentation Questions (35 Marks Total)

Students attempt one option from each question.

3. Force Measurement / Piezoelectric Pressure Sensor (7 Marks)

Option (a)
Force measurement using strain gauge:                Principle of resistance change due to strain

Wheatstone bridge configuration                           Calibration and output voltage

Option (b)
Working of piezoelectric sensor for pressure measurement.

4. Ultrasonic Flow Sensor / Hall & Capacitive Sensors (7 Marks)

Option (a)
Operating principles of ultrasonic flow sensors:                     Time-of-flight

Doppler method                                                                         Transit-time measurement

Option (b)
How Hall-effect sensor measures position + working of capacitive level sensor.

5. Graphical Programming Loops / Structures (7 Marks)

Option (a)
Explain WHILE and FOR loops in graphical programming (iteration behavior).

Option (b)
Purpose and functionality of structures in graphical programming.

6. Data Acquisition Block Diagram / Sigma-Delta ADC (7 Marks)

Option (a)
Draw block diagram of Data Acquisition System (DAQ).
Differentiate between analog IO vs digital IO.

Option (b)
Explain the operating principle of Sigma–Delta ADC.

7. Smart Sensors – Characteristics / Structure (7 Marks)

Option (a)
Characteristics of smart sensors:                        Self-calibration

Self-diagnosis                                                     Embedded processing

Communication ability                                       Miniaturization

Option (b)
General structure of smart sensors:                   Sensing element

Signal conditioning                                            ADC

Microcontroller                                                  Communication interface

Overall Purpose of the Document

This exam paper evaluates student mastery over:

Sensor Fundamentals

Types, principles, selection criteria, and characteristics.

Temperature, Pressure & Flow Measurement

RTDs, thermistors, strain gauges, piezoelectric sensors, ultrasonic sensors.

Instrumentation Systems & Data Acquisition

Counters, data sockets, analog vs digital IO, virtual instrumentation techniques.

ADC/DAC Conversions

Weighted resistor DAC, Sigma–Delta ADC.

Smart Sensors & Robotics

Applications in autonomous systems, robot control, and embedded instrumentation.

Graphical Programming

Loops, structures, block diagrams used in LabVIEW-style environments.

Overall, the exam includes definitions, numerical problems, diagrams, system explanations, and modern instrumentation concepts—ensuring complete assessment of Sensor & Instrumentation knowledge.