Use sensors to capture physical data
Match the syllabus sensor types to measured physical properties and suitable system contexts.
Section 3 · Hardware
This sequence follows Cambridge IGCSE Computer Science 0478, 2026–2028 syllabus Version 6. It covers subject content sections 3.1–3.3 only. The separately published 2029–2031 syllabus is not mapped here. Practice is original, self-checked and does not award an official Cambridge grade. Full timed papers and human subject-teacher review remain outstanding.
Before you begin
- No programming language is required. Be comfortable with place value and multiplication; each lesson introduces the computer-science notation it uses.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
What does a sensor provide to a computer?
What you will learn
- Explain what a sensor captures
- Identify the data measured by syllabus sensor types
- Select a suitable sensor for a context
A sensor converts a physical condition into data
A sensor detects a physical property and supplies a measurement to a computer. The syllabus sensor types include acoustic, accelerometer, flow, gas, humidity, infra-red, level, light, magnetic field, moisture, pH, pressure, proximity and temperature.
Apply and check the rule
Selection depends on the quantity to measure and the environment. For example, a pH sensor measures acidity/alkalinity, a moisture sensor measures water content, and a proximity sensor detects whether an object is nearby. A sensor measures; an actuator acts.
Pause and explain
A system must measure how close an object is without contact. Which sensor is suitable?
Worked example
A greenhouse must detect soil dryness before watering plants. Which sensor is suitable?
Show the worked solution
- The system needs the soil's water content.
- A moisture sensor measures moisture in the soil.
- The controller can use that measurement to decide whether to water.
Answer A moisture sensor, because it measures the soil's water content.
Try a topic test
Choose Easy, Normal or Difficult. Save your answers and open worked review after finishing.
Test this topic →From guided practice to a new situation
Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
Match each requirement to a sensor: count fluid moving through a pipe; detect room brightness; measure air temperature.
Give me a hint
Match the measured physical property.
Compare my reasoning
- Fluid movement → flow sensor.
- Brightness → light sensor.
- Air temperature → temperature sensor.
Flow; light; temperature sensors.
Look for these in your work
- Flow matched
- Light matched
- Temperature matched
A car system must detect rapid vehicle movement and the presence of nearby obstacles. Which two sensor types could help?
Give me a hint
One sensor measures acceleration; the other detects nearness.
Compare my reasoning
- An accelerometer measures acceleration or movement.
- A proximity sensor detects nearby objects.
An accelerometer and a proximity sensor.
Look for these in your work
- Movement sensor selected
- Nearness sensor selected
A fish farm monitors acidity, water level and temperature. Choose a sensor for each and explain why one sensor cannot automatically replace all three.
Give me a hint
Identify each distinct physical measurement.
Compare my reasoning
- Acidity → pH sensor.
- Water height → level sensor; warmth → temperature sensor.
- Each sensor measures a different property, so the system needs the appropriate measurement for each decision.
Use a pH sensor, level sensor and temperature sensor. They capture different physical properties and are not interchangeable.
Look for these in your work
- pH mapped
- Level and temperature mapped
- Different quantities distinguished
Common mistakes
- Using a temperature sensor to measure humidity
- Confusing a sensor with the actuator it controls
What can you explain now?
Which sensor measures acidity or alkalinity?
Compare with the explanation
pH sensor
A pH sensor measures the pH of a substance.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
What is the difference between a sensor and an actuator?
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.