Sensors and Their Applications

What is the primary function of a sensor?

• To display information.

• To store data.

• To measure physical properties from its surroundings.

• To process data.

In which of the following scenarios would a temperature sensor be most useful?

• Detecting the sound of dripping liquids.

• Controlling a central heating system.

• Switching car headlights on automatically.

• Measuring the acidity of soil.

How do light sensors produce an output based on light brightness?

• By measuring the amount of water vapor.

• By detecting nearby objects.

• By using photoelectric cells to produce electric current.

• By gauging the volumetric content of water.

Which of these is an application of an active infrared sensor?

• Monitoring the temperature inside an industrial freezer.

• Detecting body heat in a security system.

• A security alarm system that detects an intruder breaking a beam.

• Measuring acceleration in a car.

What do accelerometers primarily measure?

• Gas pressure in a nuclear reactor.

• Acceleration and motion of an application.

• The presence of nearby objects.

• The sound of footsteps in a security system.

Which of the following are examples of physical changes in nature that produce analogue data?

• Binary code and text files.

• Temperature, light, and pH.

• On/off signals from a switch.

• Numbers and symbols.

What is the main purpose of an Analogue to Digital Converter (ADC)?

• To convert digital data into analogue data.

• To convert physical values into discrete digital values.

• To store analogue data for later use.

• To process digital data in a microprocessor.

In a smart street lighting system, what causes a street lamp to switch on?

• A signal from the microprocessor when the sensor data is greater than a stored value.

• A signal from the light sensor directly to the lamp.

• A signal from the microprocessor when the sensor data is less than a stored value.

• A manual switch operated by a person.

Why does a smart street lamp stay switched on for 30 minutes after being activated, even if light conditions change briefly?

• To save energy by not switching on and off too often.

• To prevent the lamp from flickering due to temporary changes like cloud cover.

• To allow time for the microprocessor to process new data.

• To ensure the street is well-lit for a set period.

How are vehicles detected at a smart traffic junction to control the traffic lights?

• Cameras monitor the traffic flow.

• Pressure sensors built into the roads detect approaching vehicles.

• Sound sensors listen for engine noise.

• Infrared sensors detect vehicle heat.