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ScotlandEngineering Science

Area 2: Electronics and control

8 dot points across 8 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

How are voltage, current, resistance and power related in an analogue circuit?

Analogue electronics: voltage, current and resistance, Ohm's law, electrical power, and combining resistors in series and in parallel.
An SQA National 5 Engineering Science answer on analogue electronics, covering voltage, current and resistance, Ohm's law V equals IR, electrical power P equals IV, and how to combine resistors in series and in parallel in a circuit.
10 min answer →

How do we combine gates to control an output, and how do NAND gates and Boolean expressions help?

Combinational logic: combining gates to meet a control requirement, completing the truth table of a combined circuit, NAND and NOR gates, and reading a Boolean expression.
An SQA National 5 Engineering Science answer on combinational logic, covering how gates are combined to control an output, completing the truth table of a combined circuit, the NAND and NOR gates as inverted AND and OR, and writing a Boolean expression for a logic system.
10 min answer →

How do digital logic gates make decisions from high and low inputs?

Digital logic gates (AND, OR, NOT) and their truth tables, including recognising gate symbols and completing a truth table for a single gate.
An SQA National 5 Engineering Science answer on digital logic gates, covering the AND, OR and NOT gates, their symbols and truth tables, the meaning of logic 1 and logic 0, and how to complete a truth table for a single gate.
9 min answer →

How does a microcontroller use a program to control inputs and outputs?

Programmable control: the microcontroller as a programmable process sub-system and the use of flowcharts with inputs, decisions, outputs and loops to control a system.
An SQA National 5 Engineering Science answer on programmable control, covering the microcontroller as a programmable process sub-system, why programmable control is flexible, and how a flowchart uses inputs, decisions, outputs, delays and loops to control a system automatically.
9 min answer →

How does an operational amplifier compare two voltages or boost a small signal?

The operational amplifier as a comparator and as an inverting amplifier, including calculating the voltage gain and output voltage of an inverting amplifier.
An SQA National 5 Engineering Science answer on the operational amplifier, covering its use as a comparator that switches when two input voltages cross, the inverting amplifier configuration, and calculating the voltage gain and output voltage from the feedback and input resistors.
10 min answer →

How does a small sensor signal switch on a large output device like a motor or lamp?

Output devices and transistor switching: common output transducers and using a transistor as an electronic switch driven by a sensing circuit, including a protective diode.
An SQA National 5 Engineering Science answer on output devices and transistor switching, covering output transducers such as the lamp, LED, buzzer and motor, how a transistor acts as an electronic switch turned on by a small base voltage, the use of a series resistor for an LED, and a protective diode across a motor coil.
9 min answer →

How do we represent an electronic system as input, process and output?

Universal systems diagrams: representing an electronic or control system as input, process and output sub-systems using block diagrams.
An SQA National 5 Engineering Science answer on the universal systems approach, covering input, process and output sub-systems, drawing and interpreting block diagrams, the meaning of feedback, and identifying real components within each block.
8 min answer →

How do we turn a physical condition like light or heat into a changing voltage?

The voltage divider and input transducers: calculating the output voltage of a divider and using the LDR and thermistor to make light- and temperature-sensing circuits.
An SQA National 5 Engineering Science answer on the voltage divider and input transducers, covering the divider equation, how the output voltage splits in proportion to resistance, and how an LDR or thermistor makes a light- or temperature-sensing circuit that produces a changing voltage.
10 min answer →