ELECTENG 101 Electrical and Digital Systems
The Complete Exam Bible · S2 2026ELECTENG 101 Overview
- 15-point foundation course
- University of Auckland
- Semester 2, 2026
- In-person final examination
ELECTENG 101 Electrical and Digital Systems is a University of Auckland foundation course that connects electrical, computer and electronic systems. It starts with current, voltage, resistance, power and Kirchhoff laws, then develops circuit-analysis methods that remain useful throughout the course.
- Assessed by Assignments, exercises, laboratory, tests and examination
- Pass condition Overall and controlled-assessment thresholds both apply
- Exam aid One double-sided A4 sheet is permitted
- Core method Reference, equation, unit and boundary check
How ELECTENG 101 is assessed
| Component | Weight | Format |
|---|---|---|
| Formative assignments | 30% | Ten weekly online assignments, 3% each |
| In-class exercises (ICE) | 4% | Four bi-weekly in-class activities, 1% each |
| Laboratory | 4% | One laboratory in Week 10 or Week 11 |
| Tests · hurdle | 22% | Two in-person restricted-book/calculator tests, 11% each |
| Examination · hurdle | 40% | In-person restricted-book/calculator assessment; one double-sided A4 sheet permitted |
Weights and formats come from the 2026 Canvas assessment overview. The Lane 1 hurdle applies to the controlled assessments collectively, and sitting the exam is mandatory for pass eligibility.
What ELECTENG 101 covers
Ten chapters follow the published coursebook spine from electrical quantities and DC analysis to sensors, op-amps, number systems, logic, ADCs, motors, AC power and the grid.
Electrical Quantities and Circuit Laws
Current, voltage, resistance, power, KCL and KVLBuild the signed language used throughout the course. Current needs a reference arrow, voltage needs a polarity, and power direction follows the passive sign convention.
- Charge flow and current references
- Voltage polarity and common reference
- Resistance and Ohm law
- Signed power and passive convention
- Kirchhoff current and voltage laws
- Open- and short-circuit boundaries
DC Circuit Analysis Methods
Equivalent resistance, node voltage, superposition and Thevenin modelsSelect an analysis method from the unknown and the topology. Reduction works only for genuine series or parallel connections.
- Series and parallel topology
- Voltage and current division
- Node-voltage equations
- Superposition in linear circuits
- Thevenin voltage and resistance
- Load lines and short-circuit current
Sensors and Interface Circuits
Resistive transducers, divider interfaces and Wheatstone bridgesResistive transducers turn temperature, strain or another physical quantity into a resistance change. Divider and Wheatstone-bridge interfaces turn that change into a voltage that later stages can process.
- Resistive transducer laws
- Divider transfer direction
- Sensitivity around an operating point
- Wheatstone bridge balance
- Differential output polarity
- Receiver loading
Signal Conditioning and Op-Amp Circuits
Loading, buffering, gain, offset and feedbackSignal conditioning protects and reshapes sensor voltages before conversion or control. Source resistance and receiver input resistance create loading. Buffers reduce that interaction.
- Thevenin source loading
- Input and output resistance
- Voltage follower buffering
- Ideal op-amp constraints
- Inverting and non-inverting gain
- Summing and level shifting
Number Systems and Representation Limits
Base conversion, bit width and finite unsigned rangesPositional notation represents value as digits weighted by powers of a base. Binary, octal, decimal and hexadecimal conversions become reliable when every digit is paired with its place value.
- Positional place value
- Expansion into decimal
- Repeated-division conversion
- Binary-octal-hex grouping
- Unsigned code ranges
- Minimum bit width
Boolean Algebra and Logic Gates
Truth tables, identities, simplification and gate networksTruth tables, Boolean expressions and gate networks describe the same decision rule. Canonical expressions can be derived mechanically from output-one rows, then simplified with identities and checked against the original table.
- AND, OR and NOT operations
- XOR and derived gates
- Boolean identities
- De Morgan laws
- Truth-table minterms
- Expression simplification
Analog-to-Digital Conversion
Sampling, quantisation, reference range and resolutionAnalog-to-digital conversion separates time and amplitude decisions. Sampling selects observation times, quantisation maps each amplitude to a finite zone and encoding assigns a binary code.
- Sampling in time
- Quantisation zones
- Binary encoding
- Reference voltage range
- Bit depth and step size
- Saturation and clipping
DC Motors and Electromechanical Response
Commutation, back emf, torque, speed and efficiencyA permanent-magnet DC motor links armature voltage and current to torque and speed. Rotation generates back emf that opposes the supply. Load changes alter speed, back emf, current and developed torque as a causal loop.
- Magnetic force and torque
- Commutation
- Armature equivalent circuit
- Back emf and speed
- Torque and current
- Mechanical output power
AC Circuit Concepts and Power
Sinusoids, RMS, energy storage, real and reactive powerSinusoidal signals are described by amplitude, angular frequency and phase. RMS gives the DC-equivalent heating value, while capacitors and inductors link voltage and current through derivatives and energy storage.
- Cosine signal parameters
- Period and frequency
- Lead and lag
- Average and RMS values
- Capacitor and inductor laws
- Real and reactive power
Electricity Generation and Distribution
Three-phase supply, transmission and transformer ratiosElectricity supply links generation, high-voltage transmission, distribution and loads. Balanced three-phase systems use phase displacement to deliver power efficiently.
- Generation stages
- Balanced three-phase supply
- Line and phase quantities
- Transmission loss
- Transformer turns ratio
- Current ratio
The middle of the course follows a monitoring, analysis and response chain: resistive sensors create electrical changes, interface circuits and operational amplifiers condition those changes, analog-to-digital converters create finite codes, Boolean logic makes decisions, and DC motors produce mechanical response. Number systems and representation limits supply the language for the digital half.
The final topics return to physical power systems through sinusoidal signals, RMS values, capacitors, inductors, AC power, three-phase generation, transmission, distribution and transformers. Assessment combines ten online assignments, four in-class exercises, one laboratory, two controlled tests and a final examination. The controlled lane has its own threshold, so steady coursework does not replace test and exam preparation.
This guide uses original examples and diagrams to rehearse the published relationships without copying released question stems.
Worked example · free
A loaded sensor divider
- +2The loaded lower leg is 2 kΩ in parallel with 10 kΩ: 1.667 kΩ.
- +2The receiver voltage is 5 × 1.667/(3 + 1.667) = 1.786 V.
- +1It is below the unloaded 2 V result, which confirms the loading direction.
Key terms
- Back emf
- The voltage generated by a rotating motor that opposes the applied supply.
- Boolean algebra
- An algebra of binary states used to describe and simplify logic decisions.
- Kirchhoff current law
- Conservation of charge expressed as a zero algebraic sum of currents at a node.
- Kirchhoff voltage law
- Conservation of energy per charge expressed as a zero algebraic sum around a loop.
- Loading effect
- A signal change caused when a receiving input draws current from a non-ideal source.
- Node voltage
- Electric potential at a node measured relative to a declared reference node.
- Power factor
- The ratio of real power to apparent power for an AC load.
- Quantisation
- Mapping a continuous sample amplitude into one of a finite set of converter levels.
- RMS value
- The DC-equivalent value that produces the same resistive heating as a varying waveform.
- Thevenin equivalent
- A terminal model consisting of one ideal voltage source and one series resistance.
- Truth table
- A complete list of a Boolean function’s output for every input combination.
- Voltage divider
- A series-resistor network whose output is a resistance-weighted fraction of its supply.
- Wheatstone bridge
- Two dividers compared differentially to detect a change in resistance.
- Turns ratio
- The transformer winding ratio that sets the ideal voltage and inverse current ratios.
ELECTENG 101 FAQ
How is ELECTENG 101 assessed?
The published 2026 assessment is 30% formative assignments, 4% in-class exercises, 4% laboratory, 22% tests and 40% examination. The two tests and examination are controlled Lane 1 assessments, while the other components are Lane 2.
What can I take into the ELECTENG 101 exam?
The captured examination page permits one double-sided A4 sheet with anything written or printed on it and a restricted calculator. It describes an in-person restricted-book-lite exam. Check the current University instructions for venue and any later details.
Is there a hurdle in ELECTENG 101?
Yes. Passing requires at least 50% overall and at least 40% of the total weighted Lane 1 marks. Falling below the Lane 1 threshold caps the overall mark at 45%. Sitting the examination is also required for pass eligibility.
Which circuit method should I use?
Use the method that preserves the requested quantity with the least unnecessary work. Node voltage suits a few essential nodes, superposition separates independent-source effects, and a Thevenin equivalent is efficient when one external load changes.
How do the analog and digital topics connect?
A sensor changes an electrical quantity, an interface and op-amp condition the signal, an ADC quantises it into a code, and Boolean logic makes a decision. The motor topic then shows one way a decision can become physical response.
Are past final papers included?
The captured course folder includes Test 1 papers and solution commentaries for several years, including multiple 2026 versions. It does not include a past final paper, so this guide does not claim a final-paper structure.
How should I revise the formulas?
Attach each formula to its assumptions and one direction check. Practise retrieving the law, substituting signed values, naming units and checking a boundary. Only then compress the verified relationships onto the permitted A4 sheet.
Questions students ask in each ELECTENG 101 chapter
- Why can circuit current be negative?
- A negative result means the physical current runs opposite to the arrow chosen before solving. The reference remains valid; translate the sign into a direction instead of restarting the calculation. Keep the original arrow when checking KCL, because silently reversing it after seeing the answer changes the meaning of every term that used that current. Chapter 01 · Electrical Quantities and Circuit Laws
- When should I use node voltage?
- Use it when a circuit has relatively few essential nodes and branch currents can be written as voltage differences divided by resistance. A source tied to reference can set a node directly. It is especially efficient when many parallel branches meet at the same nodes, because each resistor current follows from one voltage difference instead of becoming a separate unknown. Chapter 02 · DC Circuit Analysis Methods
- Why predict the divider direction first?
- The prediction detects a swapped numerator or reversed sensor position. A lower-leg resistance increase raises the output fraction, while an upper-leg increase lowers it. Writing that direction before substituting numbers provides an independent check: if the arithmetic moves the other way, inspect the circuit placement and chosen output terminals instead of trusting the calculator. Chapter 03 · Sensors and Interface Circuits
- When may I use equal op-amp input voltages?
- Use the ideal equality only when negative feedback is present and the output is not saturated. It is not a rule for an open-loop comparator or a rail-limited result. First identify a feedback path from output to the inverting input and verify that a small output change drives the input difference back toward zero rather than reinforcing it. Chapter 04 · Signal Conditioning and Op-Amp Circuits
- Why is the unsigned maximum one less than 2ⁿ?
- There are 2ⁿ patterns, but the first represents zero. Counting from zero makes the last value 2ⁿ−1. For example, three bits create eight patterns from 000 through 111, representing unsigned values zero through seven. Keep code count and greatest value on separate lines so the subtraction is applied only to the requested quantity. Chapter 05 · Number Systems and Representation Limits
- How do I derive an expression from a truth table?
- For every output-one row, write a product containing each input in true or complemented form. OR all those minterms, then simplify. A variable appears uncomplemented when that row contains one and complemented when it contains zero. Evaluate the resulting expression on at least one output-zero row before simplifying to catch a copied bit. Chapter 06 · Boolean Algebra and Logic Gates
- What does adding ADC bits improve?
- It increases the number of amplitude codes and reduces nominal step size for a fixed reference range. It does not increase the sampling rate. Doubling the number of codes halves the ideal step width, but practical accuracy can still be limited by input noise, reference error and converter non-idealities that a bit-count calculation alone does not remove. Chapter 07 · Analog-to-Digital Conversion
- Why is motor starting current high?
- At standstill back emf is near zero, so armature current is limited mainly by the comparatively small armature resistance. That current can exceed the safe continuous value, which is why starting methods, supply limits or control electronics matter. As the rotor accelerates, rising back emf reduces current under the same applied voltage. Chapter 08 · DC Motors and Electromechanical Response
- What is the RMS value of a sine wave?
- For a sinusoid, RMS magnitude is peak magnitude divided by the square root of two. State whether a supplied value is peak or RMS before using it. The formula depends on waveform shape, so it should not be transferred automatically to a square wave or an arbitrary signal. RMS is useful because it predicts equivalent resistive heating. Chapter 09 · AC Circuit Concepts and Power
- Why transmit at high voltage?
- For a given real power and power factor, higher voltage allows lower current. Since conductor loss is I²R, the reduction in loss is squared. For example, halving line current reduces resistive loss to one quarter when resistance is unchanged. The tradeoff is greater insulation, clearance and equipment demand at higher voltage. Chapter 10 · Electricity Generation and Distribution
How to study for the exam
Work in three loops. First, rebuild the conceptual chain and explain every arrow in the figures: what changes, what stays conserved and which boundary limits the result. Second, solve original problems with references and units written before the arithmetic. Classify every error as topology, sign, formula, representation, unit or boundary, then repeat a fresh problem from that family.
Third, practise mixed retrieval under time pressure. Move between circuit laws, sensor interfaces, op-amp maps, binary codes, logic rules, motor equations and AC power without relying on chapter order. Build the permitted A4 sheet gradually. Put formulas beside assumptions, include peak-versus-RMS and line-versus-phase reminders, and reserve space for the mistakes you personally repeat.
Use the released Test 1 materials for supported circuit-reasoning roles, but do not treat them as a map of the final because the captured final structure is not published. In the last week, verify the current exam instructions and rehearse calculator operations with the restricted device you will take.
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