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ScotlandEngineering Science

Area 2: Electronics and control

7 dot points across 7 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

How do engineers model an electronic device as a system, and what is the difference between an analogue and a digital signal?

Modelling electronic devices with the input, process and output system model, and distinguishing analogue from digital signals.
An SQA Higher Engineering Science answer on modelling electronic devices with the input, process and output system model, and on the difference between analogue and digital signals with examples of each.
11 min answer →

How do you calculate currents, voltages, resistances and power in series and parallel circuits?

Ohm's law and the power relationships, and analysing series and parallel resistor networks for current, voltage, resistance and power.
An SQA Higher Engineering Science answer on Ohm's law and the power relationships, and on analysing series and parallel resistor networks to find current, voltage, total resistance and power dissipation.
12 min answer →

How do logic gates combine digital inputs to make decisions, and how do you work out the output of a combinational logic circuit?

The logic gates AND, OR, NOT, NAND and NOR with their truth tables, and analysing combinational logic circuits that combine several gates.
An SQA Higher Engineering Science answer on the logic gates AND, OR, NOT, NAND and NOR with their truth tables, and how to analyse combinational logic circuits that combine several gates to make a decision.
12 min answer →

How does an operational amplifier amplify or compare voltages, and how do you calculate the gain of an inverting amplifier?

The operational amplifier as an inverting amplifier with gain set by feedback resistors, as a difference amplifier, and as a comparator producing a switching output.
An SQA Higher Engineering Science answer on the operational amplifier as an inverting amplifier with gain set by feedback resistors, as a difference amplifier, and as a comparator that produces a switching output for control.
13 min answer →

What output devices does a control circuit drive, and how do you calculate the series resistor for an LED?

Output devices such as LEDs, buzzers, motors and solenoids, interfacing them to a control circuit, and calculating the series resistor needed to protect an LED.
An SQA Higher Engineering Science answer on output devices such as LEDs, buzzers, motors and solenoids, how they are interfaced to a control circuit, and how to calculate the series resistor that protects an LED.
11 min answer →

How does a potential divider turn a sensor's changing resistance into a changing voltage for the rest of a circuit?

The potential divider relationship and its use with input transducers such as the thermistor and the light-dependent resistor to produce a sensing voltage.
An SQA Higher Engineering Science answer on the potential divider relationship and how it is used with input transducers such as the thermistor and light-dependent resistor to produce a voltage that responds to temperature or light.
12 min answer →

How does a transistor let a small signal switch a large current, and how is an output device such as a motor protected?

The transistor as an electronic switch driven by a small input signal, used to control output devices, with a diode to protect against the back-emf of inductive loads.
An SQA Higher Engineering Science answer on the transistor as an electronic switch driven by a small input signal, how it controls output devices such as relays and motors, and why a protective diode is needed across inductive loads.
11 min answer →