Numbers
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
Fields and Their Consequences
Alternating currents
- 5 things to know
- Papers 2 and 3
Overview
Peak, peak-to-peak and root mean square values, and using an oscilloscope.
What you need to know
Answer each one before you reveal it.
Your recallNot started
Numbers
How is peak voltage found from rms voltage, and what is peak-to-peak value?
Numbers
How does an oscilloscope measure time, and what do its axes show?
Key term
What type of display does an oscilloscope produce for an ac signal?
Numbers
When mains voltage is quoted as 230 V, is this the peak value or the rms value?
Questions from this subtopic
Each one with the model answer underneath.
- 1
How does the voltage or current in a sinusoidal alternating supply vary with time?
Model answer
It varies as a sine function of time.
- 2
What is the peak value of a sinusoidal waveform?
Model answer
The maximum value reached by the current or voltage during the cycle.
- 3
Define the peak-to-peak value of a sinusoidal waveform.
Model answer
The total range from maximum positive to maximum negative value, which equals twice the peak value.
- 4
What is the root mean square (rms) value of an alternating current?
Model answer
The equivalent steady direct current that would dissipate the same power in a resistor.
- 5
State the formula relating rms current to peak current for a sinusoidal waveform.
Model answer
Iᵣₘₛ = I₀ / √2
- 6
In the equation Iᵣₘₛ = I₀ / √2, what does I₀ represent?
Model answer
The peak current (maximum value of the alternating current).
Other ways to work this
The same content, four other ways.
What is inside Levo
Six ways to work the same material.
Every question in Fields and Their Consequences, 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.
Or £46 a year, about £3.83 a month. Cancel anytime.