B3.4 Electronic systems application and selection (HL only) Questionbank

Figure 1: An image of a sensor commonly used in lighting systems.

From Figure 1, identify the type of sensor used and describe its purpose.

Figure 2: A basic setup showing an LDR (light-dependent resistor) in series with a fixed resistor connected to a microcontroller input pin.

Using Figure 2, explain how the LDR circuit works as a light sensor input.

Referring to Figure 1 and 2, outline one advantage of combining a PIR sensor with an LDR in an automatic light system.

Figure 3: A truth table and logic diagram for a system using a NOT gate and AND gate to control a light output.

i.) Using Figure 3, describe the logic behavior of the system and how the NOT gate functions.

ii.) Suggest one way the system could be improved using a microcontroller instead of only logic gates.

Design a brief sequence for how the microcontroller could operate this system, using pseudocode or steps.

Figure 1: Block diagram showing a temperature sensor connected to a microcontroller, which controls a ventilation fan.

i.) Identify two advantages of using a microcontroller in a greenhouse control system like the one shown in Figure 1.

ii.) Describe how open-loop control differs from closed-loop control in the context of Figure 1.

Figure 2: Graph comparing analog vs digital signal outputs from a moisture sensor over time.

Referring to Figure 2, explain two key differences between analog and digital signals in control systems.

Figure 3: Photo of an Arduino with relay module used to control a 12V water pump from a soil moisture sensor.

i.) State the role of the relay module in the system shown in Figure 3.

ii.) Analyse how the system in Figure 3 functions using the IPO (Input–Process–Output) model.

Justify the importance of feedback in a smart control system like the one used in the greenhouse scenario.