Exam Ready Notes
Definition: A sensor is an electronic device that detects or measures physical parameters from the environment and converts them into electrical signals that can be processed by a controller or computer. Sensors act as the "sense organs" of an IoT system.
A sensor receives a physical stimulus such as temperature, light, pressure, or motion. This causes a change in an electrical property (voltage, current, resistance, or capacitance). The sensor converts this change into an electrical signal which is then processed by the system.
Definition: An actuator is a device that converts an input signal (usually electrical) into physical action or mechanical motion. In IoT systems, actuators act as the "muscles" that perform actions based on commands from the controller.
An actuator receives a control signal from a controller or microprocessor and converts supplied energy into mechanical motion — linear, rotary, or oscillatory.
Sensors and actuators are fundamental components of IoT systems. A sensor detects physical conditions and acts as an input device, while an actuator performs physical actions based on control signals and acts as an output device.
| Parameter | Sensor | Actuator |
|---|---|---|
| Basic Function | Detects and measures physical quantities | Produces physical action or movement |
| Role in System | Input device | Output device |
| Energy Conversion | Physical quantity → Electrical signal | Electrical/fluid/air → Mechanical motion |
| Purpose | Monitoring and data collection | Control and execution |
| Position in IoT Flow | First stage | Final stage |
| Output Form | Electrical signal | Mechanical motion |
| Dependency | Sends data to controller | Acts on controller commands |
| Human Analogy | Sense organs | Muscles |
| Examples | Temperature sensor, LDR, humidity sensor | Motor, solenoid valve, hydraulic cylinder |