Home · IGCSE Computer Science 0478 · Automated and emerging technologies · Automated systems: sensors, microprocessors and actuators · Practice
IGCSE · Practice questions · Automated systems: sensors, microprocessors and actuators

Sense, compare, act.

Six original Cambridge-style questions on automated systems, from naming the parts to evaluating a system in a given scenario.

Original questions All questions on this page are original work, written in the Cambridge IGCSE style. They are not from past papers. They test the same concepts and skills the syllabus rewards.
Keep these straight

Every step, in order.

01
Recall
[3 marks]

State the purpose of each of these in an automated system: (a) a sensor, (b) a microprocessor, (c) an actuator.

  • (a) A sensor measures a physical property (e.g. temperature) and sends the data to the microprocessor. ✓
  • (b) A microprocessor processes the data: it compares it with stored values and decides what action to take. ✓
  • (c) An actuator receives a signal from the microprocessor and performs a physical action, e.g. a motor turning or a valve opening. ✓
02
Explain
[6 marks]

A museum keeps the humidity of a display room between 45% and 55% to protect old paintings. It uses a humidity sensor, a microprocessor, a humidifier and a dehumidifier. Describe how the system keeps the humidity in this range.

  • The humidity sensor measures the humidity of the room and sends the data to the microprocessor (via an ADC). ✓
  • The microprocessor compares the reading with the stored range of 45% to 55%. ✓
  • If the humidity is below 45%, the microprocessor sends a signal to switch the humidifier on (and the dehumidifier off). ✓
  • If the humidity is above 55%, it sends a signal to switch the dehumidifier on (and the humidifier off). ✓
  • If the reading is within the range, both are switched off (or left off). ✓
  • The sensor keeps taking readings, so the process repeats continuously. ✓
03
Apply
[2 marks]

Name one suitable sensor and one suitable actuator for an automatic system that turns on a fan in a school kitchen when the air becomes too smoky.

  • Sensor: gas / smoke sensor. ✓
  • Actuator: a motor that drives the fan (extractor fan). ✓
04
Analysis
[4 marks]

A city plans to replace train drivers with a fully automated (driverless) train system. Give two advantages and two disadvantages of this.

  • Advantage: trains can run closer together and more frequently because the system responds faster than a human driver. ✓
  • Advantage: no driver errors from tiredness or distraction, and lower wage costs over time (accept: more consistent braking saves energy). ✓
  • Disadvantage: very expensive to install sensors, control systems and platform doors. ✓
  • Disadvantage: a hacker or a software/sensor fault could stop trains or cause an accident; drivers lose their jobs. ✓
05
Explain
[3 marks]

A game console controller contains a gyroscope and a vibration motor. Explain how they are used together with the console's microprocessor during a racing game.

  • The gyroscope (sensor) detects how the player tilts the controller and sends the data to the microprocessor. ✓
  • The microprocessor uses the data to steer the car in the game, and decides when the car hits something. ✓
  • It then sends a signal to the vibration motor (actuator) so the player feels the crash through the controller. ✓
06
Apply
[3 marks]

A school laboratory uses an automated system to record the temperature of a reaction every 10 seconds for one hour. Give three advantages of using this system instead of a student taking readings.

  • Readings are taken at exactly the right times, so the results are more accurate and consistent. ✓
  • It can take readings over a long time without getting tired or losing concentration (and could run overnight). ✓
  • The student does not need to stay near a possibly dangerous reaction; the data is stored automatically and can be graphed straight away. ✓

Mark this once you have attempted all six and checked your working. It records a Practiced badge on the topic and adds a one-time bonus. Revealing the solutions alone does not count.