Key term
CCEA A-Level Physics 1210
Physical Quantities, Scalars and Vectors
Moments and Equilibrium
Linear Motion and Dynamics
Newton's Laws of Motion
Linear Momentum and Impulse
Work, Energy and Power
Current, Charge and Potential Difference
Resistance and Resistivity
Topic overviewResistance and Ohm's lawOhmic and non-ohmic behaviourResistors in series and in parallelInvestigating current, voltage and resistance in series and parallel circuitsElectrical power and energy in resistive circuitsResistivity and the equation R = ρl/AMeasuring the resistivity of a metalCurrent–voltage characteristics of a conductor, a lamp and a diodeResistance, temperature and superconductivity
Internal Resistance and Potential Dividers
Topic overviewInternal resistance and terminal potential differenceConsequences of internal resistance for external circuitsMeasuring electromotive force and internal resistanceThe potential divider and variable outputPotential dividers in lighting and heating control circuitsLoaded potential dividers and output voltage calculations
Waves
Refraction
Lenses
Superposition, Interference and Diffraction
Topic overviewSuperposition of wavesStanding waves, nodes and antinodesStanding waves on stretched stringsStanding waves in a pipe closed at one endMeasuring the speed of sound with a resonance tubeConditions for observable interferencePath difference and phase differenceYoung's double slitDiffraction at a single slitThe diffraction grating
Quantum Physics
Wave-Particle Duality
Astronomy
Practical Skills and Data Analysis
Topic overviewChoosing and using measuring instrumentsPrecision, accuracy and recording measurementsUsing the cathode ray oscilloscope to measure voltage and frequencyTables, graphs and presenting resultsLinearising a relationship and using the gradientAbsolute and percentage uncertaintyCombining uncertainties and uncertainty on a graphRandom and systematic error, reliability and refining an experiment
Deformation of Solids
Thermal Physics
Topic overviewBoyle's law, Charles's law and the pressure lawThe ideal gas equation pV = nRTThe Avogadro constant, the mole and pV = NkTInternal energy and the distribution of molecular energyThe kinetic theory equation pV = ⅓Nm⟨c²⟩Average molecular kinetic energy and temperatureAbsolute zero and the kelvin scaleSpecific heat capacity and the electrical method
Uniform Circular Motion
Simple Harmonic Motion
Topic overviewDefining simple harmonic motion and a = −ω²xDisplacement, velocity and acceleration: x = A cos ωtThe simple pendulum and T = 2π√(l/g)The loaded spiral spring and T = 2π√(m/k)SHM graphs and finding velocity from a gradientFree vibrations, forced vibrations and resonanceDamping: light, critical and over-damping
The Nucleus and Radioactive Decay
Topic overviewAlpha-particle scattering and the nuclear atomNuclear radius and nucleon numberThe density of nuclear matterAlpha, beta and gamma radiation: nature, penetration and rangeNuclear equations and changes in nucleon and proton numberThe random and exponential nature of radioactive decayActivity, the decay constant and A = −λNExponential decay calculations with A = A₀e^(−λt)Half-life and measuring it
Nuclear Energy, Fission and Fusion
Gravitational Fields
Electric Fields
Capacitors
Magnetic Fields
Charged Particles and Accelerators
Deformation of Solids
Measuring the Young modulus of a wire
- 3 things to know
- Unit A2 1
Overview
Recall questions on the apparatus and why the wire is long and thin, measuring the diameter with a micrometer in several places and two directions, finding the area, what is plotted and what the gradient gives, the purpose of the comparison wire, the tensioning load, checking the elastic limit has not been passed, and the safety precautions.
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
When measuring the Young modulus, why is the test wire made as long and as thin as is practical?
Key term
In a Young modulus experiment, which instrument is used to measure the diameter of the wire, and what is its precision?
Questions from this subtopic
Each one with the model answer underneath.
- 1
Describe the apparatus used to measure the Young modulus of a metal in the form of a long thin wire.
Model answer
A long wire is clamped firmly at one end, run over a pulley at the edge of a bench or hung vertically from a ceiling clamp, and loaded with slotted masses at the free end. A marker taped to the wire is read against a millimetre scale fixed alongside it.
- 2
Why is the test wire made as long and as thin as is practical?
Model answer
A long thin wire gives the largest extension for a given load, so the extension is measured with a much smaller percentage uncertainty.
- 3
Which instrument is used to measure the diameter of the wire, and what is its precision?
Model answer
A micrometer screw gauge is used, reading to 0.01 mm.
- 4
Why is the diameter of the wire measured at several places along it and in two directions at each place?
Model answer
The wire may not be perfectly uniform along its length or perfectly circular in section, so a mean diameter gives a more reliable cross-sectional area.
- 5
How is the cross-sectional area of the wire found from its diameter?
Model answer
A = πd²/4, where d is the mean diameter in metres and A the area in m².
- 6
Why is the diameter of the wire usually the largest source of uncertainty in this experiment?
Model answer
The diameter is a very small quantity to measure and it is squared when the area is calculated, so its percentage uncertainty is doubled in the final value of E.
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