In the ECET 2026 Computer Science syllabus, IoT (Internet of Things) is a growing and high-weightage topic. One of the most scoring sub-topics is Sensors & Actuators. Without them, IoT devices can’t interact with the physical world. Questions from this topic are direct and often repeated. Let’s revise the complete concept, followed by 10 most expected MCQs with answers and explanations.
📘 Concept Notes – Sensors & Actuators in IoT
🌐 What is IoT?
- IoT connects physical devices to the internet, enabling them to sense, collect, and share data.
- Examples: Smart home devices, health monitoring systems, industrial automation.
🔍 Sensors
- Definition: Devices that detect physical parameters (like temperature, light, motion) and convert them into electrical signals.
- Function in IoT: Collect real-time data from the environment.
- Examples:
- Temperature Sensor (DHT11, LM35)
- Light Sensor (LDR)
- Motion Sensor (PIR)
- Gas Sensor (MQ series)
- Key Points:
- Input device (data flows from physical world to system)
- Used in smart homes, agriculture, healthcare, etc.
⚙️ Actuators
- Definition: Devices that convert electrical signals into physical action.
- Function in IoT: Perform actions based on processed data.
- Examples:
- Motor
- Relay
- Solenoid Valve
- Servo Motor
- Key Points:
- Output device (system sends signal to actuator)
- Used for automation, control systems.
🔄 How They Work Together
- Sensor detects environmental changes.
- Data sent to microcontroller/cloud.
- Decision-making logic processes data.
- Actuator performs the required action.
Example:
A smart irrigation system →
Soil moisture sensor detects dryness → Controller triggers water pump actuator → Irrigation starts automatically.
🔟 10 Most Expected MCQs – ECET 2026 [IoT – Sensors & Actuators]
Q1. Which of the following is an input device in IoT?
A) Motor
B) Relay
C) Temperature Sensor
D) Buzzer
Q2. PIR sensor is used to detect:
A) Pressure
B) Motion
C) Temperature
D) Light
Q3. Which device converts physical parameters into electrical signals?
A) Sensor
B) Actuator
C) Controller
D) Transistor
Q4. A servo motor in IoT is an example of:
A) Sensor
B) Actuator
C) Controller
D) None
Q5. LDR is used to measure:
A) Light intensity
B) Humidity
C) Temperature
D) Motion
Q6. Which sensor is used in smart smoke detection systems?
A) PIR Sensor
B) MQ-2 Sensor
C) LDR
D) LM35
Q7. In IoT, the role of actuators is to:
A) Sense environment
B) Process data
C) Perform actions
D) Store data
Q8. Which of the following is NOT an actuator?
A) DC Motor
B) Servo Motor
C) Temperature Sensor
D) Solenoid Valve
Q9. Soil moisture sensor in IoT agriculture helps in:
A) Detecting light levels
B) Measuring soil wetness
C) Controlling humidity
D) Pumping water directly
Q10. What is the correct sequence in IoT operation?
A) Sensor → Data Processing → Actuator
B) Actuator → Sensor → Processing
C) Processing → Sensor → Actuator
D) Actuator → Processing → Sensor
✅ Answer Key Table
| Q.No | Answer |
|---|---|
| Q1 | C |
| Q2 | B |
| Q3 | A |
| Q4 | B |
| Q5 | A |
| Q6 | B |
| Q7 | C |
| Q8 | C |
| Q9 | B |
| Q10 | A |
🧠 Explanations of All Answers
- Q1 → C: Temperature sensor is an input device.
- Q2 → B: PIR sensors detect motion.
- Q3 → A: Sensors convert physical quantities to signals.
- Q4 → B: Servo motor is an actuator used for precise motion control.
- Q5 → A: LDR measures light intensity.
- Q6 → B: MQ-2 detects smoke and harmful gases.
- Q7 → C: Actuators execute physical actions.
- Q8 → C: Temperature sensor is a sensor, not an actuator.
- Q9 → B: Measures soil wetness to automate irrigation.
- Q10 → A: Data flows from sensor → processing → actuator.
🎯 Why This Practice Matters for ECET 2026
IoT concepts are relatively new but high-scoring in ECET. Most questions are direct factual MCQs, and remembering sensor-actuator types can easily give you full marks in this section. It’s also relevant for real-world smart technology applications.
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