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Types of Sensors and Their Working Principles: High Quality Notes
1. Temperature Sensors
Types:
- Thermocouples: Measure temperature using two different metals joined at one end. Voltage difference created correlates to temperature.
- RTDs (Resistance Temperature Detectors): Change in resistance of metal with temperature.
- Thermistors: Resistance decreases with increase in temperature.
Working Principle:
- Thermocouples: Produce a voltage that varies with temperature.
- RTDs: Use a material (often platinum) whose resistance changes predictably with temperature.
- Thermistors: Use semiconductor materials with resistance inversely related to temperature.
2. Proximity Sensors
Types:
- Inductive: Detect metal objects.
- Capacitive: Detect any material that changes the dielectric constant.
- Ultrasonic: Use sound waves to detect objects.
- Photoelectric: Use light to detect objects.
Working Principle:
- Inductive: Produce an electromagnetic field and detect changes when metal objects enter.
- Capacitive: Measure changes in capacitance when objects approach.
- Ultrasonic: Emit ultrasonic waves and measure reflection time.
- Photoelectric: Emit a beam of light and detect reflection or interruption.
3. Pressure Sensors
Types:
- Strain Gauge: Measures deformation.
- Capacitive: Measures change in capacitance.
- Piezoelectric: Measures electrical charge generated by pressure.
Working Principle:
- Strain Gauge: Convert physical deformation into electrical resistance change.
- Capacitive: Measure changes in capacitance caused by diaphragm movement.
- Piezoelectric: Generate electrical charge when pressure is applied to a piezoelectric material.
4. Light Sensors
Types:
- Photodiodes: Convert light into current.
- Phototransistors: Similar to photodiodes but provide amplification.
- LDRs (Light Dependent Resistors): Change resistance with light intensity.
Working Principle:
- Photodiodes: Generate current proportional to light intensity.
- Phototransistors: Provide amplified electrical response to light.
- LDRs: Decrease resistance as light intensity increases.
5. Motion Sensors
Types:
- PIR (Passive Infrared): Detects infrared light from warm objects.
- Ultrasonic: Uses sound waves.
- Microwave: Uses microwaves to detect motion.
Working Principle:
- PIR: Detect infrared radiation changes.
- Ultrasonic: Emit sound waves and measure reflection changes.
- Microwave: Emit microwaves and detect changes in their reflection.
6. Humidity Sensors
Types:
- Resistive: Measure resistance change with humidity.
- Capacitive: Measure capacitance change with humidity.
- Thermal Conductivity: Measure changes in thermal conductivity.
Working Principle:
- Resistive: Use materials whose resistance changes with humidity.
- Capacitive: Use materials whose dielectric constant changes with humidity.
- Thermal Conductivity: Measure changes in the rate of thermal transfer.
7. Gas Sensors
Types:
- Electrochemical: Generate current by chemical reaction.
- Infrared: Measure absorption of infrared light.
- Semiconductor: Measure changes in electrical conductivity.
Working Principle:
- Electrochemical: React with target gas and produce electrical signal.
- Infrared: Measure gas concentration by infrared light absorption.
- Semiconductor: Change conductivity when gas interacts with sensor surface.
Summary | Types of Sensors and Their Working Principles
Understanding Sensors:
- Sensors convert physical phenomena into readable electrical signals.
- Each sensor type is designed for specific measurements and operates on distinct principles.
Applications:
- Sensors are crucial in various applications including industrial automation, environmental monitoring, healthcare, and consumer electronics.
Importance:
- Accurate sensor data is vital for control systems, safety, and efficient operation of devices and processes.
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