Key term
WJEC AS-Level Physics 1420QS
Basic Physics
Kinematics
Dynamics
Energy Concepts
Solids Under Stress
Using Radiation to Investigate Stars
Particles and Nuclear Structure
Topic overviewQuarks, leptons and hadronsThe four interactions and conservation lawsThe first generation of quarks and leptonsAntiparticles and annihilationBaryons, antibaryons and mesonsDeducing quark compositions from chargeBeta decay and quark flavour changeTesting a reaction against the conservation rules
Conduction of Electricity
Resistance
Topic overviewCalculating resistance from resistivityPotential difference, Ohm's law and powerResistivity, temperature and superconductivityThe volt: energy transferred per unit chargeCurrent–voltage characteristics of non-ohmic componentsMeasuring resistance and resistivity in the laboratoryThe heating effect of a current and choosing a power equationThermistors and how a semiconductor's resistance falls with temperatureConductance, conductivity and comparing materials
D.C. Circuits
Topic overviewKirchhoff's laws, and resistors in series and parallelPotential dividers, emf and internal resistanceCells, resistivity, power and energyWorking out currents and potential differences in resistor networksSensor circuits with thermistors and LDRsInternal resistance, power transfer and short-circuit currentAmmeters, voltmeters and their effect on the circuit
The Nature of Waves
Wave Properties
Topic overviewEnergy transfer and the wave equationTransverse and longitudinal waves, path difference and intensityDiffraction and superpositionTwo-source interference and the diffraction gratingStationary wavesHow much a wave spreads at a gap or an obstacleCoherence and the conditions for observable interferenceYoung's double slit and λ = ay/DMeasuring wavelength with a diffraction gratingMeasuring the speed of sound with stationary waves
Refraction of Light
Photons
Topic overviewPhoton energy and the electronvoltThe photoelectric effectStopping potential and the Planck constantThe photoelectric effect and photon energiesLine spectra and energy levelsDemonstrating the photoelectric effectThe electromagnetic spectrum and typical photon energiesElectron diffraction and the de Broglie relationshipRadiation pressure
Lasers
Mathematical Requirements (Appendix C)
Topic overviewSignificant figures and arithmetic meansUncertainty and how uncertainties combineAlgebraic symbols and proportionalityRearranging and solving equationsSmall angle approximationsTangents and instantaneous rates of changeAreas under curves and numerical methodsReading a tangent on a motion graphStraight-line graphs and y = mx + cWhat a gradient and an intercept representLinearising a relationship to find a constantLog plots of exponential decayChoosing what to plot to find a constantLogarithmic scales and orders of magnitudeWorking with base-ten logarithmsThe shapes of common graphsInverse and root relationships on a graphAreas, volumes and PythagorasGeometry applied to physical situationsSubstituting into physical equationsTrigonometry and right-angled trianglesResolving a force into componentsRadians, arc length and force diagramsRandom processes and translating between representationsMean values and periodic functionsSymbols for approximation and comparison
Conduction of Electricity
- 5 subtopics
- 15 things to know
- AS Unit 2
What Conduction of Electricity covers
Conduction of Electricity is examined on AS Unit 2 of WJEC Physics, Electricity and Light. 64 recall questions across 5 subtopics.
The 5 subtopics
Each one has its own page. WJEC AS Physics students sit this topic in the first year.
- Current, charge and the ampereRecall questions on Current, charge and the ampere.Open →
- Drift velocity and the equation I = nAvqRecall questions on Drift velocity and the equation I = nAvq.Open →
- The coulomb and the charge on an electronRecall questions on The coulomb and the charge on an electron.Open →
- Conductors, insulators and other charge carriersRecall questions on Conductors, insulators and other charge carriers.Open →
- The free-electron model and the speed of conductionRecall questions on The free-electron model and the speed of conduction.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
State the equation relating current to drift velocity, and define its symbols.
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State the equation that relates current, charge, and time.
Key term
What is drift velocity?
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What is the SI unit of electric charge, and what symbol is used for it?
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State the magnitude of the charge carried by a single electron.
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Name the charge carriers in an aqueous solution of copper(II) sulfate.
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In an electrolyte, in which directions do the positive and the negative ions drift?
Key term
Describe the structure of a metal as it is pictured in the free-electron model.
Key term
State the order of magnitude of the random thermal speed of a free electron in a metal at room temperature.
Key term
What is electric current?
Key term
State the equation relating current to drift velocity.
Numbers
How many electrons must pass a point in a circuit to carry one coulomb of charge?
Key term
Name the charge carriers present in an ionised gas.
Key term
Why do the electrons settle to a steady drift velocity instead of accelerating continuously along the wire?
Take Conduction of Electricity further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Conventional current vs Electron flow
Conventional current: the flow taken to run from positive to negative. Electron flow: the movement of the charge carriers themselves, from negative to positive.
Drift velocity vs Number density
Drift velocity: the average velocity of the charge carriers along a conductor. Number density: the count of charge carriers in each unit volume of the material.
Questions from this topic
Each one with the model answer underneath.
- 1
What is electric current?
Model answer
Electric current is the rate of flow of electric charge through a conductor.
- 2
State the equation that relates current, charge, and time.
Model answer
I = Q/t, where I is current in amperes, Q is charge in coulombs, and t is time in seconds.
- 3
In the equation I = Q/t, what does I represent and what is its unit?
Model answer
I represents current, measured in amperes (A).
- 4
Calculate the current when charge = 78 C, time = 35 s.
Model answer
Current = 78 ÷ 35 = 2.23 A.
- 5
Define one ampere.
Model answer
One ampere is defined as a current of one coulomb per second.
- 6
In which direction does conventional current flow?
Model answer
Conventional current flows from positive to negative.
What is inside Levo
Six ways to work the same material.
Conduction of Electricity revision questions
- Is Conduction of Electricity examined at AS in WJEC Physics?
- Yes. It sits in AS Unit 2, which you take in the first year, so it is on the AS paper as well as counting towards the full A level.
- What does Conduction of Electricity cover in WJEC AS-Level Physics?
- 5 subtopics: current, charge and the ampere, drift velocity and the equation i = navq, the coulomb and the charge on an electron, conductors, insulators and other charge carriers and the free-electron model and the speed of conduction. Each one has its own page with questions and model answers.
- How is Conduction of Electricity organised?
- By the WJEC 1420QS specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Conduction of Electricity, 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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