A home appliance company is designing an automatic bathroom light system that turns on when someone enters, dims based on ambient light, and switches off after a set time delay using a basic logic circuit.
(a)
Figure 1: An image of a sensor commonly used in lighting systems.
From Figure 1, the type of sensor used and its purpose.
[2]
(b)
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, how the LDR circuit works as a light sensor input.
[2]
(c)
Referring to Figure 1 and 2, three advantages of combining a PIR sensor with an LDR in an automatic light system.
[3]
(d)
Figure 3: A truth table and logic diagram for a system using a NOT gate and AND gate to control a light output.
Using Figure 3, the logic behavior of the system and how the NOT gate functions.
[4]
(e)
one way the system could be improved using a microcontroller instead of only logic gates.
[1]
(f)
a brief sequence for how the microcontroller could operate this system, using pseudocode or steps.
[6]
HLPaper 2
A design team is developing a smart agricultural monitoring system to maintain crop health in remote greenhouses. The system uses sensors, control logic, and actuators to detect environmental changes and respond automatically.
(a)
Figure 1: Block diagram showing a temperature sensor connected to a microcontroller, which controls a ventilation fan.
two advantages of using a microcontroller in a greenhouse control system like the one shown in Figure 1.
[2]
(b)
how open-loop control differs from closed-loop control in the context of .
HLPaper 1
What type of circuit configuration allows current to split across multiple paths?
HLPaper 2
The smart thermostat in Figure 1 controls a domestic heating system. The user sets a target temperature, shown here as 20 degrees Celsius, and the thermostat then holds the room at that temperature on its own. A sensor reads the room temperature, the thermostat compares that reading with the target, and the boiler is switched on or off in response. The reading is taken continuously, so the system keeps correcting itself as the room warms up or cools down.
Figure 1: Smart thermostat, showing a target temperature of 20 on its display
(a)
the input device used by the thermostat.
[1]
(b)
HLPaper 2
Lumire Cycles manufactures the LED bicycle lamp shown in Figure 2. Inside the lamp, a 6 V battery drives a driver circuit containing three resistors connected in series, of 10 ohms, 20 ohms and 30 ohms, which limit the current reaching the LED. The rider switches the lamp on with the button on the top of the housing.
Figure 2: LED bicycle lamp mounted on the handlebar, showing the lens and the switch on top of the housing
(a)
whether a resistor is a passive or an active component.
[1]
(b)
IB Design Technology (First Exam 2027) Topic B3.4 Electronic Systems Application and Selection Questionbank
Practice IB Design Technology (First Exam 2027) Topic B3.4 Electronic Systems Application and Selection with authentic exam-style questions for both SL and HL students. This question bank focuses on the exact syllabus content for B3.4 Electronic Systems Application and Selection and mirrors Paper 1, 2 style where relevant.
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Figure 1
[3]
(c)
Figure 2: Graph comparing analog vs digital signal outputs from a moisture sensor over time.
Referring to Figure 2, two key differences between analog and digital signals in control systems.
[4]
(d)
Figure 3: Photo of an Arduino with relay module used to control a 12V water pump from a soil moisture sensor.
the role of the relay module in the system shown in Figure 3.
[1]
(e)
how the system in Figure 3 functions using the IPO (Input–Process–Output) model.
[6]
(f)
the importance of feedback in a smart control system like the one used in the greenhouse scenario.
[4]
the difference between an open-loop and a closed-loop electronic system.
[2]
(c)
the purpose of the feedback loop in the thermostat shown in Figure 1.
[3]
(d)
one problem that a negative feedback system can suffer from.
[1]
one active component used in electronic systems.
[1]
(c)
the function of the resistors in the driver circuit of the LED lamp.
[3]
(d)
why the LED in the lamp is classified as a digital output device.
