← IGCSE Computer Science Paper 1

Matching sensors to the data they capture

Each sensor captures one type of data, so identify the data first (e.g. moisture in soil, humidity in air), then name the sensor that measures it.

Part of: IGCSE Computer Science 0478 — 3.2 Input and Output Devices — Module 49, IGCSE Computer Science 0478 — 6.1 Automated Systems — Module 24, ACARA Digital Technologies Years 7–8 — Acquiring and Storing Data — Module 19, ACARA Digital Technologies Years 9–10 — Acquiring and Validating Data — Module 28, QCE Digital Solutions Unit 3 — Interactions Between Users, Data and Digital Systems — Module 76

Understanding Matching sensors to the data they capture in IGCSE Computer Science Paper 1

What it does: Infra-red sensors detect heat radiation from people and objects, so they capture this data. Humidity is water vapour in the air. Moisture is water in a solid such as soil. Identify the data first, then pick the sensor. Sound is the data, so use an acoustic sensor. Pressure sensors measure force on a surface or the pressure of a gas or liquid, not sound. Accelerometers measure changes in speed, movement and tilt. Magnetic field sensors detect magnets and metal. A level sensor measures how full a container is. A flow sensor measures how fast a liquid or gas moves through a pipe.

Common mistakes: Water in soil is measured by a moisture sensor. A humidity sensor measures water vapour in the air. Line 1 should be sensor = "moisture". Brightness is measured by a light sensor. A proximity sensor detects how close an object is. Line 2 should be sensor = "light".

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This module's key terms are also in a printable crossword (Modules 293–303) and word search (Modules 283–303).

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Learning
Duo
A greenhouse system must measure the amount of water vapour in the air. Which sensor captures this data?
Humidity sensorMoisture sensor
Matches
Soil dryness in a greenhouse -> humidity sensor
↓
Humidity measures water vapour in the air. Soil water content is moisture, so it needs a moisture sensor.
Applying
Meanings
Term
data first, then sensor
Meaning
Each sensor captures one type of data, so identify the data first (e.g. moisture in soil, humidity in air), then name the sensor that measures it.
Practice
CASE OF data
Testing
Gaps
sensor ← " sensor"
Check Answer
Spots
1sensor = "humidity"
2data = "water in the soil"

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Quick Questions

1. A greenhouse system must measure the amount of water vapour in the air. Which sensor captures this data?
A. Humidity sensor ✓
B. Moisture sensor
Humidity is water vapour in the air. Moisture is water in a solid such as soil. Identify the data first, then pick the sensor.
2. A garden system must check how wet the soil is before watering the plants. Which sensor captures this data?
A. Moisture sensor ✓
B. Humidity sensor
Water in soil is moisture. Humidity sensors measure water vapour in the air, not water in a solid.
3. An intruder alarm must detect the body heat of a person entering a room. Which sensor captures this data?
A. Proximity sensor
B. Infra-red sensor ✓
Infra-red sensors detect heat given off by objects or people. Proximity sensors measure how close an object is.
4. A car reversing system must warn the driver how close the bumper is to a wall. Which sensor captures this data?
A. Proximity sensor ✓
B. Infra-red sensor
The data is the distance to a nearby object, so the sensor is a proximity sensor. Infra-red sensors detect heat.
5. A smart alarm must detect the sound of breaking glass. Which sensor captures this data?
A. Pressure sensor
B. Acoustic sensor ✓
Sound is the data, so use an acoustic sensor. Pressure sensors measure force on a surface or the pressure of a gas or liquid, not sound.

Match the Pairs

moisture sensor → Measures the amount of water in soil or another solid material
humidity sensor → Measures the amount of water vapour in the air
Data captured: heat given off by a moving person, as used in a burglar alarm → infra-red sensor
Data captured: how close an object is, as used in a car parking aid → proximity sensor
Soil dryness in a greenhouse -> humidity sensor → Humidity measures water vapour in the air. Soil water content is moisture, so it needs a moisture sensor.
Loudness of a crowd -> pressure sensor → Sound is captured by an acoustic sensor. A pressure sensor measures force on a surface or the pressure of a gas or liquid.

Key Term

data first, then sensor
Each sensor captures one type of data, so identify the data first (e.g. moisture in soil, humidity in air), then name the sensor that measures it.

Fill in the Blanks

1. data ← "water content of soil" sensor ← "moisture sensor"
Hint: Name the sensor that measures how wet the soil is, not the air.
2. data ← "water vapour in the air" sensor ← "humidity sensor"
Hint: Name the sensor that measures water vapour in the air, not in soil.
3. data ← "heat given off by a person" sensor ← "infra-red sensor"
Hint: Name the sensor that detects heat given off by living things.
4. data ← "force pressing down on a bed mat" sensor ← "pressure sensor"
Hint: Name the sensor that measures force pressing on a surface, not sound.
5. data ← "sound level in a classroom" sensor ← "acoustic sensor"
Hint: Name the sensor that captures sound, not force or touch.

Spot the Error

Question 1
A sensor = "humidity"
B data = "water in the soil"
C print(sensor, "measures", data)
Line A — Water in soil is measured by a moisture sensor. A humidity sensor measures water vapour in the air. Line 1 should be sensor = "moisture".
Question 2
A data = "brightness of a room"
B sensor = "proximity"
C print("Use a", sensor, "sensor")
Line B — Brightness is measured by a light sensor. A proximity sensor detects how close an object is. Line 2 should be sensor = "light".
Question 3
A data = "loudness of a classroom"
B print("Data:", data)
C sensor = "pressure"
Line C — Sound level is captured by an acoustic sensor. A pressure sensor measures force on a surface, not sound. Line 3 should be sensor = "acoustic".
Question 4
A data = "water moving in a pipe"
B sensor = "level"
C print(data, "->", sensor)
Line B — Water moving along a pipe is measured by a flow sensor. A level sensor measures how full a container is. Line 2 should be sensor = "flow".
Question 5
A m = {}
B m["air vapour"] = "humidity"
C m["soil water"] = "moisture"
D m["acidity"] = "gas"
Line D — Acidity is the data captured by a pH sensor. A gas sensor detects gases in the air. Line 4 should be m["acidity"] = "pH".

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