Unit 6.1 - Sensors and Uses

Question 1

example applications of temperature sensors

Answer 1

-control central heating system
-control / monitor chemical process
-control / monitor greenhouse temperature

Question 2

moisture sensors

Answer 2

sensor that measures water levels (in soil)

Question 3

examples of moisture sensors

Answer 3

-control / monitor moisture levels in soil in greenhouse
-monitor moisture levels in food processing factory

Question 4

humidity sensor

Answer 4

sensor that measures amount of water vapour (in air)

Question 5

humidity sensor examples

Answer 5

-monitor humidity levels in building and microchip manufacture factory
-monitor / control humidity levels in air in greenhouse

Question 6

light sensor

Answer 6

sensor that uses photoelectric cells that produce an output depending on the brightness of the light

Question 7

light sensor examples

Answer 7

-switching street lights on or off
-switch on car headlights automatically when dark

Question 8

infrared (active) sensors

Answer 8

sensor that uses an invisible beam of infrared radiation picked up by a detector, if beam is broken, there is a change in the amount of infrared radiation reaching the sensor

Question 9

infrared (active) sensor examples

Answer 9

-turn on car wipers automatically when rain is detected on windscreen
-security alarm system (intruder breaks infrared beam)

Question 10

infrared (passive) sensors

Answer 10

sensor that measures heat radiation given off by an object (temperature)

Question 11

infrared (passive) sensors examples

Answer 11

-security alarm system (detects body heat)
-monitor temperature inside industrial freezer/chiller

Question 12

pressure sensors

Answer 12

Transducer and generates different electric currents depending on pressure applied

Question 13

pressure sensor examples

Answer 13

-weighing lorries at weighing station
-measure gas pressure in nuclear reactor

Question 14

acoustic/sound sensors

Answer 14

microphone that convert detected sound into electrical signals/pulses

Question 15

acoustic/sound sensor examples

Answer 15

-detects noise of footsteps in security system
-detects sound of liquid dripping at faulty pipe joint

Question 16

Gas sensors

Answer 16

detects gas being monitored and produce outputs that vary with gas levels present

Question 17

gas sensor examples

Answer 17

-monitor pollution levels in air (at airport)
-monitor O2 and CO2 levels in greenhouse
-monitor oxygen levels in car exhaust

Question 18

pH sensors

Answer 18

measure acidity through changes in voltages (in soil)

Question 19

pH sensors examples

Answer 19

-monitor / control acidity levels in soil in greenhouse
-control acidity levels in chemical process

Question 20

magnetic field sensors

Answer 20

-measure changes in magnetic fields (signal output depends on magnetic field changes)

Question 21

magnetic field sensor examples

Answer 21

-detect magnetic field changes (in phones and CD players)
-used in anti-lock braking systems in cars

Question 22

accelerometer sensors

Answer 22

measure acceleration and motion of an application (change in velocity)

Question 23

accelerometer sensor examples

Answer 23

-measure rapid deceleration and apply air bags in a crash in cars
-changes between portrait and landscape mode in phones

Question 24

proximity sensors

Answer 24

detect presence of a nearby object

Question 25

proximity sensor examples

Answer 25

-detect when a face is close to a mobile phone screen
–>switches off screen when held to the ear

Question 26

flow (rate) sensors

Answer 26

measure the flow rate of a moving liquid / gas and produce an output based on the amount of liquid / gas passing over the sensor

Question 27

flor (rate) sensor examples

Answer 27

-respiratory devices and inhalers in hospitals
-measures gas flows in pipes

Question 28

level sensors

Answer 28

use ultrasonics to detect changing liquid levels (in tanks) or conductivity to measure static levels (height of water in a river)
–>it can be optical or mechanical in nature

Question 29

level sensor examples

Answer 29

-monitor levels in a petrol tank in cars
-powder levels in tablet production need to be monitored (pharmaceutical process)
-leak detection is refrigerant (AC)

Question 30

temperature sensors

Answer 30

measures temperature of surrounds by sending signals that change as temperature changes