Sensors Flashcards
Define a sensor (2)
input devices
read physical properties from surroundings
Temperature sensor description (2)
measures temperature of surroundings by sending signals
temperature changes = signals change
Examples of temperature sensors (3)
control central heating system
control chemical process
control temperature in greenhouse
Moisture sensor description
measures water levels
Examples of moisture sensors (2)
control soil moisture levels in greenhouse
monitor moisture levels in food processing factory
Description of humidity sensor
measures amount of water vapour in air sample
Examples of humidity sensors (2)
monitor humidity levels in building
monitor humidity levels in greenhouse
Description of light sensors (2)
use photoelectric cells
produce output depending on light brightness
Examples of light sensors (2)
switching street lights on/off
switching car lights on/off
Description of pressure sensors (2)
transducer
generates different electric currents depending on pressure applied
Examples of pressure sensors (2)
weighing of lorries
measuring gas pressure in nuclear reactor
Description of proximity sensor
detect presence of nearby object
Examples of proximity sensors
detect when face is close to mobile phone
Description of infrared active sensors (2)
use invisible infrared beam
beam broken = change in amount of infrared reaching detector
Examples of infrared active sensors (2)
security alarm system
activating windscreen wipers
Description of infrared passive sensors
measure heat radiation given by object
Examples of infrared passive sensors (2)
security alarm system
monitor temperature
Description of acoustic/sound sensors
microphones that convert sound into electric signals/pulses
Examples of acoustic/sound sensors
pick up noise in security
Description of gas sensors
detect gas being monitored and produce outputs
Examples of gas sensors (2)
monitor pollution levels
monitor gas levels in greenhouse
Description of pH sensors
measure acidity through changes in voltage
Examples of pH sensors (2)
acidity in soil
acidity in chemical processes
Description of accelerometer sensor
measure motion of object
Examples of accelerometer sensors (2)
apply air bags in car
mobile phones = change between landscape and portrait
Description of flow sensor
measure flow rate of liquid/gas and produce output
Examples of flow sensor (2)
measure gas flow in pipes
respiratory devices
Description of level sensor
detect changing liquid levels
Examples of level sensors (2)
petrol tank
pharmaceutical process
7 mark sensor answer (7)
Sensor name
Sensor send signal which converts analogue to digital using ADC
Microprocessor compares digital value (ADC value) with stored value (in the question)
If it’s within range nothing happens
If it’s outside ange signal is sent to actuator
does something (according to question)
system operates in a continuous loop
