Key term
AQA A-Level Physics 7408
Measurements and Their Errors
Particles and Radiation
Topic overviewConstituents of the atomStable and unstable nucleiParticles, antiparticles and photonsParticle interactionsClassification of particlesQuarks and antiquarksApplications of conservation lawsThe photoelectric effectCollisions of electrons with atomsEnergy levels and photon emissionWave-particle duality
Waves
Mechanics and Materials
Electricity
Further Mechanics and Thermal Physics
Fields and Their Consequences
Topic overviewFieldsNewton's lawGravitational field strengthGravitational potentialOrbits of planets and satellitesCoulomb's lawElectric field strengthElectric potentialCapacitanceParallel plate capacitorEnergy stored by a capacitorCapacitor charge and dischargeMagnetic flux densityMoving charges in a magnetic fieldMagnetic flux and flux linkageElectromagnetic inductionAlternating currentsTransformers
Nuclear Physics
AstrophysicsOptional topic
Topic overviewAstronomical telescope consisting of two converging lensesReflecting telescopesSingle dish radio telescopes, I-R, U-V and X-ray telescopesAdvantages of large diameter telescopesClassification by luminosityAbsolute magnitude, MClassification by temperature, black-body radiationPrinciples of the use of stellar spectral classesThe Hertzsprung-Russell (HR) diagramSupernovae, neutron stars and black holesDoppler effectHubble's lawQuasarsDetection of exoplanets
Medical PhysicsOptional topic
Topic overviewPhysics of visionDefects of vision and their correction using lensesEar as a sound detection systemSensitivity and frequency responseDefects of hearingSimple ECG machines and the normal ECG waveformUltrasound imagingFibre optics and endoscopyMagnetic resonance (MR) scannerThe physics of diagnostic X-raysImage detection and enhancementAbsorption of X-raysCT scannerImaging techniquesHalf-lifeGamma cameraUse of high-energy X-raysUse of radioactive implantsImaging comparisons
Engineering PhysicsOptional topic
Turning Points in PhysicsOptional topic
Topic overviewCathode raysThermionic emission of electronsSpecific charge of the electronPrinciple of Millikan's determination of the electronic charge, eNewton's corpuscular theory of lightSignificance of Young's double slits experimentElectromagnetic wavesThe discovery of photoelectricityWave–particle dualityElectron microscopesThe Michelson-Morley experimentEinstein's theory of special relativityTime dilationLength contractionRelativistic mass and energy
ElectronicsOptional topic
Topic overviewMOSFET (metal-oxide semiconducting field-effect transistor)Zener diodePhotodiodeHall effect sensorDifference between analogue and digital signalsLC resonance filtersThe ideal operational amplifierInverting amplifier configurationNon-inverting amplifier configurationSumming amplifier configurationReal operational amplifiersCombinational logicSequential logicAstablesPrinciples of communication systemsTransmission mediaTime-division multiplexingAmplitude (AM) and frequency modulation (FM) techniques
Electronics
- 18 subtopics
- 65 things to know
- Paper 3, section B
- Paper 3 Section B, one optional topic of five
What Electronics covers
Electronics is one of the five optional topics, sat on Paper 3. It covers the semiconductor devices and sensors used to detect a signal, the operational amplifier circuits used to condition it, digital logic, and the systems used to transmit it.
Where it is assessed
Paper 3, section B
One optional topic, chosen from five.
Check the AQA specification ↗The 18 subtopics
Each one has its own page.
- MOSFET (metal-oxide semiconducting field-effect transistor)The gate, source and drain, the threshold voltage, and using a MOSFET as a switch.Open →
- Zener diodeThe characteristic in forward and reverse bias, breakdown voltage, and voltage regulation.Open →
- PhotodiodeResponsivity, photo-conductive mode, and detecting particles with a scintillator.Open →
- Hall effect sensorHow a Hall sensor detects a magnetic field, and its use in a tachometer.Open →
- Difference between analogue and digital signalsBits and bytes, sampling rate, quantisation, and pulse code modulation.Open →
- LC resonance filtersThe resonant frequency of a parallel LC circuit, bandwidth, and the Q factor.Open →
- The ideal operational amplifierInfinite gain and input resistance, zero output resistance, and the two input terminals.Open →
- Inverting amplifier configurationThe gain formula, the virtual earth, and the phase inversion at the output.Open →
- Non-inverting amplifier configurationThe gain formula, why the minimum gain is one, and the phase relationship.Open →
- Summing amplifier configurationThe weighted sum of several inputs, and the difference amplifier that rejects a common signal.Open →
- Real operational amplifiersFinite gain, the gain-bandwidth product, slew rate and offset voltage.Open →
- Combinational logicThe gates and their truth tables, and building larger functions from NAND or NOR.Open →
- Sequential logicFlip-flops, the clock, binary and Johnson counters, and the reset and up/down inputs.Open →
- AstablesThe RC time constant, mark-to-space ratio and duty cycle, and varying the running frequency.Open →
- Principles of communication systemsThe block diagram of a real-time system, and the role of the transmitter and channel.Open →
- Transmission mediaMetal wire, optic fibre and radio, and the trade-offs of bandwidth, attenuation and interference.Open →
- Time-division multiplexingInterleaving sampled signals into frames, and keeping transmitter and receiver in step.Open →
- Amplitude (AM) and frequency modulation (FM) techniquesModulating a carrier by amplitude or frequency, the bandwidth each needs, and reading the waveforms.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
Why does an N-channel enhancement MOSFET not conduct at zero gate voltage?
Numbers
How does drain current behave in the linear region of MOSFET operation?
Key term
What does a Zener diode's characteristic curve look like, and what is its breakdown voltage?
Key term
What are the anode and cathode of a Zener diode, and how is the cathode marked?
Process
What happens to the voltage across a Zener diode as the reverse current through it increases beyond the breakdown point?
Numbers
How is responsivity defined, and what units does it take?
Numbers
How does photocurrent vary with light intensity, and why does reverse bias improve response?
Process
How does a scintillator and photodiode detect an atomic particle, and what does the pulse amplitude tell you?
Key term
For what application is photovoltaic mode typically used?
Key term
What does a Hall effect sensor detect in a tachometer, and what output does it give?
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How do a Hall effect sensor's pulses give rotational speed, and what besides speed can such a sensor monitor?
Numbers
What is a bit, how many make a byte, and how is decimal 5 written in binary?
Numbers
What are sampling, sampling rate and quantisation?
Numbers
How do bits per sample relate to quantisation levels and signal quality?
Evaluation
What practical disadvantage arises from converting between analogue and digital?
Key term
What is noise in communication systems?
Numbers
What is the resonant frequency of a parallel LC circuit, and what does L represent?
Numbers
How is the Q factor calculated, and what does f₀ represent?
Numbers
What does a high Q factor tell you about bandwidth and the resonance peak?
Process
How does the shape of the resonance peak change when the Q factor of an LC filter decreases?
Numbers
Why does an ideal op-amp draw no input current, and what supply does it need?
Numbers
How are the two inputs labelled, and what sets the output voltage?
Numbers
When analysing an operational amplifier circuit, should you consider its internal circuitry?
Numbers
What does the minus sign in the inverting gain formula mean, how is gain set, and how does the output's polarity compare with the input's?
Numbers
Why is no current assumed to enter the inverting input?
Numbers
What is virtual earth, and at what voltage does it hold the input?
Numbers
How is the gain of a non-inverting amplifier calculated, and what is its minimum?
Numbers
When does a non-inverting amplifier reach unity gain, and what is its phase relationship?
Numbers
What does Rꜰ stand for, and how does the phase behaviour differ from the inverting circuit?
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What is the output of a summing amplifier, and what sets each input's contribution?
Numbers
What does the minus sign mean, what sign is the output for positive inputs, and how are the inputs given different weightings?
Numbers
What does a difference amplifier do with a signal common to both inputs?
Numbers
What is the gain-bandwidth product, and how are frequency response axes scaled?
Numbers
What is needed to find bandwidth from the gain-bandwidth product, what formula gives it, and how is it widened?
Numbers
What is slew rate, and why might a real op-amp output something with equal inputs?
Process
Explain what happens to the bandwidth of an op-amp circuit if the closed-loop gain is increased
Key term
What effect does reducing the closed-loop gain of an op-amp circuit have on its bandwidth?
Numbers
How does a NAND gate relate to an AND gate, and what rule defines an OR gate?
Numbers
How many rows of an OR truth table give 1, and when does a NOR gate output 1?
Numbers
What is a truth table, and how are gates combined into larger functions?
Numbers
When constructing a logic circuit from a truth table, which rows of the truth table are relevant?
Key term
Which single gate type, other than NOR, is functionally complete?
Process
What does the clock input do, and what is fed back in a Johnson counter?
Key term
What do the reset and up/down inputs do, and what do the outputs represent?
Numbers
How many states does a 4-bit counter cycle through, and how many does a Johnson counter give?
Numbers
How many of the possible 4-bit states does a BCD counter use?
Numbers
How do frequency and period relate, and what is the period of a clock pulse?
Numbers
What is the formula for an RC time constant, what happens to an astable's frequency if C is reduced, and what does the product RC give?
Numbers
What mark-to-space ratio gives a 50% duty cycle, and how is the frequency varied?
Process
What happens to the oscillation frequency of an astable if the resistance in the RC timing network is increased?
Process
What is a communication system for, and what makes one real-time?
Key term
What does the transmitter do, and what is the transmission channel for?
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What is the role of the destination in a communication system?
Evaluation
What are the advantages and drawbacks of optic fibre against metal wire?
Process
How does wavelength affect diffraction, and how do satellites relay signals?
Evaluation
How do satellites relay signals between ground stations, why do uplinks and downlinks use different frequencies, and what is de-sensing?
Numbers
Compare the cost considerations for metal wire, optic fibre and wireless transmission
Process
How are input signals sampled, combined and sent in time-division multiplexing?
Key term
What is a frame in time-division multiplexing, and what signals is it used with?
Numbers
What is bandwidth, how is AM bandwidth calculated, and what is it when fₘ = 9900 Hz?
Numbers
What does Δf represent, and why does FM need more bandwidth than AM?
Key term
How is the carrier frequency read from an FM waveform, what do its compressed and expanded regions show, and how is the information frequency found?
Process
How does available bandwidth affect the data capacity of a channel?
Key term
Which transmission medium offers the greatest available bandwidth?
Take Electronics further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Analogue signal vs Digital signal
Analogue signal: continuously varying signal. Digital signal: signal represented by discrete levels.
Inverting amplifier vs Non-inverting amplifier
Inverting amplifier: output has opposite polarity to input. Non-inverting amplifier: output retains input polarity.
Negative feedback vs Positive feedback
Negative feedback: output fraction opposes the input. Positive feedback: output fraction reinforces the input.
Questions from this topic
Each one with the model answer underneath.
- 1
Describe the basic structure of a MOSFET in terms of its terminals and the insulating layer.
Model answer
A MOSFET consists of a semiconductor channel between drain and source terminals, with a gate terminal separated from the channel by a thin metal-oxide insulating layer.
- 2
What is the function of the drain terminal in a MOSFET?
Model answer
The drain is the terminal through which charge carriers leave the channel.
- 3
Define the source terminal in a MOSFET.
Model answer
The source is the terminal through which charge carriers enter the channel.
- 4
What role does the gate terminal play in a MOSFET?
Model answer
The gate controls the conductivity of the channel by the application of a voltage.
- 5
What does VDS represent in MOSFET terminology?
Model answer
VDS is the voltage between the drain and source terminals.
- 6
Define VGS for a MOSFET.
Model answer
VGS is the voltage between the gate and source terminals.
What is inside Levo
Six ways to work the same material.
Electronics revision questions
- What does Electronics cover in AQA A-Level Physics?
- 18 subtopics: mosfet (metal-oxide semiconducting field-effect transistor), zener diode, photodiode, hall effect sensor, difference between analogue and digital signals, lc resonance filters, the ideal operational amplifier, inverting amplifier configuration, non-inverting amplifier configuration, summing amplifier configuration, real operational amplifiers, combinational logic, sequential logic, astables, principles of communication systems, transmission media, time-division multiplexing and amplitude (am) and frequency modulation (fm) techniques. Each one has its own page with questions and model answers.
- How is Electronics organised?
- By the AQA 7408 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Electronics, on a schedule.
Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.
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