IOT Questions and Answers – Humidity Sensor

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This set of IOT Multiple Choice Questions & Answers (MCQs) focuses on “Humidity Sensor”.

1. DHT11 is __________ sensor.
a) Proximity sensor
b) Humidity sensor
c) Touch sensor
d) Pressure sensor

Explanation: We can read data from any sensor and analyse it graphically from anywhere in the world. Here, we can read temperature and humidity data from DHT11 sensor and upload it to a Think speak cloud using Arduino Uno.

2. What is ESP8266?
a) Sensor
b) WIFI module
c) Board
d) USB cable

Explanation: ESP8266 is a WIFI module, which is serial. And also it is small, cheap, and easy to use.

3. What is humidity sensor?
a) Hygrometer
b) Gyroscope
c) Sesimoscope
d) Sundial

Explanation: A hygrometer is an instrument used for measuring the water vapor in the atmosphere. Humidity measurement instruments usually rely on measurements of some quantity such as temperature, pressure, mass or a mechanical or electrical change.
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4. Units for Humidity sensor____________
a) Dew/fost point or Relative Humidity
b) Relative Humidity or Parts Per Million
c) Dew/fost point or Parts Per Million
d) Dew/fost point or Parts Per Million or Relative Humidity

Explanation: Most common units used for humidity measurement are Relative Humidity(RH), DEW/Frost point (D/F PT) and Parts Per Million(PPM). RH is a function of temperature. DEW/Frost point is a function of the pressure of the gas but is independent of temperature and is therefore defined as absolute humidity measurement of temperature. PPM is also an absolute measurement.

5. Dew point and Fost point are mainly used in which conditions?
a) Water vapor
b) Pressure of gas
c) Dryness of gas
d) Moisture in gas

Explanation: Dew point and Frost point are often used when the dryness of the gas is important. Dew point is also used as an indicator of water vapor in high temperature processes, such as industrial drying.
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6. Units for Absolute Humidity is ________
a) grams/m3
b) % by volume
c) PPMV
d) %

Explanation: Absolute Humidity is defined as ratio of mass (vapor) to volume and has units of grams/m3.

7. Units for Dew point is _______
a) gram/m3
b) % by volume
c) PPMV
d) oC

Explanation: Dew point is defined as temperature at which the water vapor in a gas condenses to liquid water and has a units of oC.

8. Humidity sensors are divided into how many types and depending on what?
a) 2 types depending on output
b) 2 types depending on measurement units
c) 3 types depending on measurement units
d) 3 types depending on output

Explanation: According to the measurement units, humidity sensors are divided into two types: Relative Humidity(RH), and Absolute Humidity(moisture) sensors. Most humidity sensors are relative humidity sensors and use different sensing principles.

9. Electronic type hygrometers are divided into how many types?
a) 5 types
b) 3 types
c) 4 types
d) 2 types

Explanation: Electronic type hygrometers or humidity sensors can broadly divided into two categories: one employs capacitive sensing principle, while other use resistive effects.

10. Relative humidity is a function of ________
a) Ambient temperature
b) Water vapor pressure
c) Ambient temperature and Water vapor pressure
d) Dryness

Explanation: Relative humidity is a function of both ambient temperature and water vapor pressure. Therefore there is a relationship between relative humidity, the amount of moisture present in the sensor, and sensor capacitance. This relation governs the operation of a capacitive humidity instrument.

11. Which sensors measure the moisture level using humidity?
a) Capacitive Sensor
b) Resistive Sensor
c) Thermal Conductivity
d) Both resistive and conductive

Explanation: Capacitive sensors measure moisture levels using a humidity dependent condenser; they are suitable for RH range and condensation tolerance. These sensors are commonly used in industrial and commercial environments.

12. ________ sensors measure the electrical change in devices such as conductive polymers.
a) Capacitive Sensor
b) Resistive Sensor
c) Thermal Conductivity
d) Both resistive and conductive

Explanation: Both resistive and conductive sensors can measure the electrical change in devices such as conductive polymers and treated substrates. They are suitable for use in residential and commercial environments.

13. ________ sensors are suitable for environments that have high temperatures.
a) Capacitive Sensor
b) Resistive Sensor
c) Thermal Conductivity
d) Both resistive and conductive

Explanation: Thermal Conductivity sensors are suitable for use in environments that have high temperatures. They measure humidity by calibrating the difference between the thermal conductivity of dry air and that of moist air.

14. Are capacitive sensors linear?
a) True
b) False

Explanation: Capacitive type sensors are linear and hence can measure RH from 0% to 100%, but require complex circuit and also need regular calibration.

15. Capacitive RH sensors dominate __________ measurements.
a) Atmospheric
b) Process
c) Both atmospheric and process
d) Neither atmospheric nor process

Explanation: Capacitive RH sensors dominate atmospheric and process measurements and are the only types of full range RH measuring devices capable of operating accurately down to 0% RH.

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