About this previous year paper
SECTION A — Short Answers (2 × 10 = 20)
(a) Difference between a Sensor and a Transducer
| Parameter | Sensor | Transducer |
|---|---|---|
| Definition | Detects physical change (like temperature, pressure, light). | Converts one form of energy to another (non-electrical → electrical). |
| Output | Non-electrical (may be mechanical, thermal, etc.) | Electrical signal proportional to the physical quantity. |
| Example | Thermistor, LDR | Thermocouple, LVDT |
(b) Advantages of Electrical Transducers
Electrical signals are easy to amplify, process, and transmit over long distances.
They offer high sensitivity and quick response. Compact and lightweight design.
Compatible with digital data acquisition systems.
(c) Properties of a Thermocouple
Seebeck Effect: Generates voltage proportional to temperature difference between junctions.
Wide Temperature Range: -200°C to +1800°C depending on material type.
Rugged, inexpensive, and suitable for dynamic temperature measurements.
(d) RTD — Full Form & Difference from Thermistor RTD: Resistance Temperature Detector.
Difference:
| RTD | Thermistor |
|------|-------------|
| Made of metals (usually platinum). | Made of semiconductor materials. |
| Has linear resistance–temperature relation. | Highly nonlinear but more sensitive. |
| Expensive, slower response. | Cheaper, faster response. |
(e) What are Imaging Sensors?
Devices that convert light into electrical signals to form digital images.
Types: CCD (Charge Coupled Device) and CMOS (Complementary Metal Oxide Semiconductor) sensors used in cameras, robotics, and surveillance.
(f) Why Image Processing is Needed? To enhance image quality (contrast, noise removal).
To extract useful information (object detection, measurement).
For automation, pattern recognition, and quality inspection.
(g) Need for Signal Conditioning Converts weak sensor outputs into usable form.
Performs amplification, filtering, linearization, and A/D conversion.
Ensures accurate, noise-free data for controllers or microprocessors.
(h) Applications of DAC (Digital-to-Analog Converter)
Converts digital signals from computers/microcontrollers into analog form.
Used in motor speed control, waveform generation, audio systems, and process control.
(i) Self-Calibration in Smart Sensors
Smart sensors use microprocessors to auto-correct for drift, temperature variation, or aging effects.
Ensures long-term accuracy.
Reduces manual recalibration needs.
(j) Need of Industrial Robots
Perform repetitive, hazardous, or precision-based tasks.
Increase productivity, safety, and consistency in manufacturing.
Used in assembly, welding, painting, and inspection.
SECTION B — Descriptive Questions (Any 3 × 10 = 30)
(a) Classification of Transducers
Based on Energy Conversion: Active (self-generating) / Passive (requires external power).
Based on Function: Primary / Secondary.
Based on Output Signal: Analog / Digital.
Based on Principle: Resistive, Inductive, Capacitive, Piezoelectric, etc.
(b) Proximity & Vibration Sensors
Proximity Sensor: Detects object presence using electromagnetic or optical fields.
Accelerometer (Vibration Sensor): Converts acceleration (vibration) into electrical output using piezoelectric effect.
(c) Imaging Sensors — CCD vs CMOS
| Parameter | CCD | CMOS |
|---|---|---|
| Power Consumption | High | Low |
| Image Quality | High, less noise | Moderate, more noise |
| Speed | Slow | Fast |
| Cost | Expensive | Economical |
| Use | Cameras, Astronomy | Smartphones, Robotics |
(d) Data Acquisition System (DAS)
Includes sensor → signal conditioner → ADC → computer.
Example: Temperature monitoring using RTD sensor, amplifier, ADC, and display system.
(e) Structure of Smart Sensors
Contains:
Sensing element Signal conditioning circuit Microprocessor for processing
Communication interface (wired/wireless)
SECTION C — Long Answers (Any 1 from each Q)
3(a) Optical Encoder
Converts rotary or linear motion into digital pulses.
Consists of light source, rotating disc with slots, and photodetector.
Used for speed and position measurement in robotics, CNC machines.
4(a) Thermistor vs RTD
Already covered — Thermistor is semiconductor-based, highly sensitive but nonlinear; RTD is metal-based, precise but slower and costlier.
4(b) Thermal Imaging
Uses infrared radiation to create images showing temperature variations.
Applications: Electrical fault detection Medical diagnostics
Night vision and surveillance Industrial safety monitoring
5(a) Machine Vision vs Computer Vision
| Aspect | Machine Vision | Computer Vision |
|---|---|---|
| Purpose | Industrial automation | General image understanding |
| Environment | Controlled (factory) | Real-world (dynamic) |
| Hardware | Cameras, sensors, lighting | Software-heavy (AI, deep learning) |
| Example | Quality control | Face recognition |
6(a) Functions of Signal Conditioning
Amplification Filtering Isolation Linearization
Analog-to-Digital conversion
6(b) Counters vs Timers
| Feature | Timer | Counter |
|---|---|---|
| Function | Measures time intervals | Counts pulses or events |
| Input | Internal clock | External pulses |
| Example | Stopwatch | Event counter |
7(a) Smart Sensors in Smart Cities
Used for air quality monitoring, traffic control, waste management, street lighting, and smart parking.
Enable data-driven IoT-based urban management.
7(b) Electric Vehicles in India — Present Scenario
Rapid adoption with FAME II and EV policy initiatives.
Major players: Tata, Ola Electric, Ather, BYD.
Growing charging infrastructure, expected to reach 30% EV penetration by 2030.