Sensor

Sensor


Sensor are devices that perform input function in a system as they sense the changes in quantity.

The best example of a sensor is mercury thermometer.

A sensor is a device which can quantitatively measure a certain physical quantity and converts a physical quantity into an electrical signal.


Classification of Sensor

    • All the sensor can be classified into two types based on the power or signal requirement. They are Active sensor and passive sensor.
    • Active Sensor:
      • this type of sensor produce output signal with help of external excitation supply. In order to operate active sensor, require power signal from an external source. 
      • Strain gauge is an example of active sensor.
    • Passive Sensor: 
      • it produces output signal without the help of external excitation supply. They do not need any extra stimulus or voltage. 
      • A thermocouple is a passive sensor which generates a voltage value corresponding to heat, applied. It does not need any power supply.

    Types of Sensor


    1. Position : a position sensor measures the position of an object; the position measurement can be either in absolute terms (absolute position sensor) or in relative terms (displacement sensor). Position sensors can be liner, angular, or multi-axis.

    2. Occupancy and motion : Occupancy sensor detects the presence of people and animals in surveillance area, while motion sensor detects movement of people and object.

    3. Velocity and Acceleration : Velocity (speed of motion) sensor may be linear or angular, indicating how fast an object moves along a straight line or how fast it rotates. 

    4. Force : Force sensor detects whether a physical force is applied and whether the magnitude of force is beyond a threshold. Example touch sensor.

    5. Pressure : Pressure sensor are related to force sensor and measure the force applied by liquids or gases.

    6. Flow : Flow sensor detect the rate of fluid flow. They measure the volume (mass flow) or rate (flow velocity) of fluid that has passed through a system in a given period of time.

    7. Acoustic : Acoustic sensor measure sound levels and convert that information into digital or analog data signal.

    8. Humidity : Humidity is defined as the amount of water present in the surrounding air.

    9. Light : Light sensor detects the presence of light. For example infrared sensor, photo detector.

    10. Radiation : Radiation sensor detect radiations in the environment. Radiation can be sensed by scintillating or ionization detection.

    11. Temperature : Temperature sensor measure the amount of heat or cold that is present in a system.

    12. Chemical : Chemical sensor measure the concentration of chemicals in a system.

    13. Image : Image sensor are instruments which are used to convert optical image into electronic signal for displaying or storing files electronically. For example thermal image device, radar, sonar, biometric etc.

    14. Optical : Optical sensor measure the physical quantity of light rays and covert it into electrical signal which cab be easily readable by user or an electronic instrument/device is called optical sensor.  For example fiber optics, Pyrometer, photo detector etc.

    15. Gas : gas sensor plays a major role in detecting the gas leakage. These gas sensor are classified into various type based on the type of gas that to be detected.

    16. Ultrasonic : ultrasonic means the range of the frequencies. Its range is greater than audible range (>20 kHz) so even it is switched on, you can’t sense these sound signals.

    17. Hall : Hall sensor is used to detect the magnetic field and gives output in terms of voltage.

    18. Infrared Sensor (IR) : it is used to certain characteristics of its surroundings by either emitting or detecting infrared radiation.

    19. Biosensors : Biosensor detects various biological elements such as organisms, tissue, cells, enzymes, antibodies,

    20. Micro and nano-sensors : micro sensor (sometimes also called MEMS) are the miniaturized version of the conventional macro sensor with improved performance and reduced cast. 

    Criteria to Choose a Sensor


    • Range 
    • Resolution
    • Accuracy
    • Precision
    • Sensitivity
    • Ruggedness
    • Linearity
    • Hysteresis
    • Response Time
    • Bandwidth
    • Resonance
    • Stability
    • Repeatability
      • Cost
        • Power Consumption
          • Type of Sensing
            • Signal-to-noise ratio
              • Operating Temperature

                Qus. 1 : Which sensor is used in mobile phones?

                1. Capacitive touch sensor
                2. Temperature sensor
                3. Humidity sensor
                4. Weight sensor
                Qus. 2 : Global Sensor Network is built for _____

                1. Reducing cost and time for development
                2. Reducing cost and increasing time for development
                3. Increasing cost and increasing time for development
                4. Increasing cost and decreasing time for development
                Qus. 3 : The smallest difference that a sensor can detect is:

                1. Scale
                2. Accuracy
                3. Resolution
                4. Precision
                Qus. 4 : In a capacitive type humidity sensor, how many different types of failures have you seen?

                1. 2
                2. 4
                3. 6
                4. 3
                Qus. 5 : DHT 11 is

                1. Microprocessor
                2. Motion Sensor
                3. Switching Device
                4. Humidity Sensor
                Qus. 6 : Which of the following is a function of a sensor?

                1. Separate physical parameters
                2. Activate response
                3. Track & transfer data to processor
                4. Move a robotic arm
                Qus. 7 : Sensor generates an output signal based on_____

                1. Input
                2. Data
                3. Physical
                4. None of These
                Qus. 8 : Which of the following is used to capture data from the physical world in IoT devices?

                1. Sensors
                2. Actuators
                3. Microprocessors
                4. Microcontrollers
                Qus. 9 : What is the use of the IR Sensor?

                1. Humidity Detection
                2. Image Processing
                3. Object Detection
                4. GPS
                Qus. 10 : LDR sensor works on the principle of

                1. Resistivity
                2. Photoconductivity
                3. Conductivity
                4. Both (A) and (C)
                Qus. 11 : What is the efficiency of the DC motor at maximum power

                1. 90%
                2. 100%
                3. Around 80%
                4. less than 50 %
                Qus. 12 : Sensor effectiveness depends on which of the following parameters

                1. Radiation
                2. Resistivity
                3. Sensitivity
                4. All of the above
                Qus. 13 : MQ-135 is a type of

                1. Humidity sensor
                2. Gas sensor
                3. Light sensor
                4. Temperature sensor
                Qus. 14 : Barometer is which type of sensor______ .

                1. Pressure sensor
                2. Touch sensor
                3. Temperature sensor
                4. Humidity sensor
                Qus. 15 : _____ is monitored using temperature sensor and data is stored / analysed locally.

                1. Room temperature
                2. Sensors
                3. Actuators
                4. None of the above
                Qus. 16 : Touch screen devices use which sensor?

                1. Capacitive Touch sensor
                2. Temperature sensor
                3. Humidity sensor
                4. Pressure sensor
                Qus. 17 : Which of the following sensor is non contact type sensor that detects the presence of an object?

                1. Proximity sensor
                2. Temperature sensor
                3. light sensor
                4. Pressure sensor
                Qus. 18 : DHT22 sensor is used to sense:

                1. Obstacles
                2. Resistance
                3. Position
                4. Humidity
                Qus. 19 : _____ devices that perform input function in a system as they sense the changes in a quantity.

                1. Sensors
                2. Arduino IDE
                3. Bluetooth
                4. Scanner
                Qus. 20 : Which type of phone sensor is used in screen brightness adjustment?

                1. Hall effect sensor
                2. Ambient Light sensor
                3. Gyroscope
                4. Proximity sensor
                Qus. 21 : These sensor do not require an external power source to monitor an environment

                1. active
                2. microcomputer
                3. range
                4. passive
                Qus. 22 : The components of a sensor node is _____ .

                1. Radio transceiver
                2. Microcontroller
                3. An electronic circuit
                4. All the above
                Qus. 23 : Which devices measures gases or liquid ?

                1. Proximity sensor
                2. Pressure sensor
                3. Temperature sensor
                4. None of these
                Qus. 24 : DHT11 is ____ sensor.

                1. Proximity sensor
                2. Humidity sensor
                3. Touch sensor
                4. None of these
                Qus. 25 : Which of these statements regarding sensors is TRUE?

                1. sensors are input devices
                2. sensors can be analog as well as digital
                3. sensors respond to some external stimuli
                4. All of these
                Qus. 26 : Which of these statements regarding Sensors are True.

                1. Sensors are input devices
                2. Sensors can be analog or digital
                3. Sensors respond to some external stimuli
                4. All of the Above
                Qus. 27 : Which sensor can detect nearby objects?

                1. Proximity sensor
                2. Humidity sensor
                3. Touch sensor
                4. Pressure sensor
                Qus. 28 : Which sensor measure the pressure relative to atmospheric pressure?

                1. Absolute pressure sensor
                2. Gauge pressure sensor
                3. Vacuum pressure sensor
                4. Differential pressure sensor
                Qus. 29 : A_ ___ tends to convert physical attribute to an electrical signal.

                1. Sensor
                2. Compiler
                3. Actuator
                4. Motors

                Programs

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