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Topic 1: Mechanics and Materials

The four equations of uniformly accelerated motion, and when they apply: v = u + at s = ut + ½at² v² = u² + 2as s = (u + v)t / 2 Only for uniform (constant) acceleration.
What do the gradient and the area of a velocity–time graph give?: Gradient: acceleration. Area under the line: displacement. (Gradient of a displacement–time graph: velocity.)
How do you solve a projectile problem?: Treat horizontal and vertical motion independently. Horizontal: constant velocity (no drag). Vertical: acceleration g = 9.81 m s⁻² downwards. Time links the two: find it from the vertical motion.
Velocity of a projectile at its maximum height: The vertical component is zero, but the horizontal component is unchanged, so the velocity is not zero.
Newton’s second law in its general form: Resultant force = rate of change of momentum, F = Δp/Δt. For constant mass this reduces to F = ma.
Newton’s third law: If body A exerts a force on body B, B exerts a force on A that is equal in size, opposite in direction and of the same type.
Explain how an object falling through air reaches terminal velocity: As its speed rises, drag increases until it equals the weight. The resultant force, and so the acceleration, is then zero, and the velocity is constant.
Moment of a force, and the principle of moments: Moment = F × x, where x is the perpendicular distance from the line of action of the force to the axis. In equilibrium, the sum of clockwise moments about any point = the sum of anticlockwise moments.
60 N hangs 0.8 m left of a central pivot. Where must 40 N hang on the right to balance?: 40 × d = 60 × 0.8 = 48, so d = 1.2 m
Momentum, and where impulse fits: p = mv, a vector in kg m s⁻¹. Unit 1 uses conservation of linear momentum in one dimension. Impulse = FΔt = Δp (the area under a force–time graph) is Unit 4 topic 4.3.
What is conserved in elastic and in inelastic collisions?: Momentum is conserved in all collisions (no external force). Kinetic energy is conserved only in elastic collisions; in inelastic ones some becomes thermal energy, sound and deformation.
Work done by a force at an angle θ to the displacement: W = Fs cos θ. Only the component along the displacement does work, so a force perpendicular to the motion does no work.
Two expressions for power: P = W/t, and P = Fv for a force F moving its point of application at velocity v.
Core Practical 1: Determine the acceleration of a freely-falling object (g), using light gates or strobe/video photography.
Density, and upthrust: ρ = m/V. Upthrust = weight of fluid displaced = ρgV (ρ the fluid’s density, V the volume displaced).
Stokes’ law, and when it applies: F = 6πηrv, the viscous drag on a small sphere of radius r moving at speed v. Only for small spheres at low speed in laminar flow.
Forces on a sphere falling at terminal velocity in a liquid: Weight = upthrust + viscous drag (three forces). Leaving out upthrust is the usual error.
How does viscosity change with temperature?: For liquids it decreases as temperature rises. For gases it increases.
Hooke’s law: F = kΔx: extension is proportional to the applied force, up to the limit of proportionality.
Elastic vs plastic deformation: Elastic: the material returns to its original shape when the force is removed. Plastic: the deformation is permanent.
Stress, strain and the Young modulus: stress = F/A (Pa) strain = Δx/x (no unit) E = stress/strain = Fx/(AΔx) E is a property of the material, not of the specimen.
A 2.00 m wire (area 1.5 × 10⁻⁷ m²) extends 3.0 mm under 45 N. Young modulus?: stress = 45 ÷ 1.5 × 10⁻⁷ = 3.0 × 10⁸ Pa strain = 0.0030 ÷ 2.00 = 1.5 × 10⁻³ E = 2.0 × 10¹¹ Pa
Core Practical 3: why is a long, thin wire used to find the Young modulus?: Long, so the extension is large enough to measure. Thin, so a modest load gives a large stress. Measure the diameter at several points with a micrometer.
Elastic strain energy: The area under the force–extension graph. In the linear region, E = ½FΔx.
Strong: Has a high breaking stress.
Stiff: Has a high Young modulus.
Tough: Absorbs a lot of energy before it fractures.
Brittle: Breaks with no plastic deformation (glass, for example).
Ductile: Can undergo large plastic deformation, so it can be drawn into a wire (copper, for example).

Topic 2: Waves and Electricity

Wave equation and period: v = fλ, T = 1/f
Why does polarisation show that light is a transverse wave?: Only transverse waves have oscillations in more than one plane perpendicular to the direction of travel, so only they can be polarised. Sound (longitudinal) cannot be polarised.
Refractive index and Snell’s law: n = c/v n₁ sin θ₁ = n₂ sin θ₂
Two conditions for total internal reflection: Light travels from a medium of higher refractive index to one of lower refractive index, and the angle of incidence is greater than the critical angle (sin C = n₂/n₁).
Coherent sources: Sources with the same frequency and a constant phase difference. Needed for a stable interference pattern.
Path difference for constructive and destructive interference (sources in phase): Constructive: path difference = nλ. Destructive: path difference = (n + ½)λ.
How does a stationary wave form, and how far apart are the nodes?: Two waves of equal frequency and amplitude travel in opposite directions and superpose. Adjacent nodes are λ/2 apart.
Speed of a transverse wave on a stretched string (Core Practical 5): v = √(T/μ), where T is the tension and μ the mass per unit length.
Diffraction grating equation: nλ = d sin θ, where d is the slit spacing and n the order.
589 nm light falls on a grating with 500 lines per mm. First-order angle?: d = 1/(500 × 1000) = 2.0 × 10⁻⁶ m sin θ = 589 × 10⁻⁹ ÷ 2.0 × 10⁻⁶ = 0.2945 θ = 17.1°
Huygens’ construction: Every point on a wavefront acts as a source of secondary wavelets; the new wavefront is the envelope of these wavelets. Used to explain diffraction.
Photon energy, and the photoelectric equation: E = hf = hc/λ hf = φ + ½mv²max
Work function and threshold frequency: Work function φ: the minimum energy needed to remove an electron from the metal surface. Threshold frequency f₀: below it, no electrons are emitted at any intensity (hf₀ = φ).
Why does the photoelectric effect support a particle model of light?: One photon gives all its energy to one electron, and energy is not accumulated. So below f₀ there is no emission however intense the light; above it emission is instantaneous; intensity changes only the rate of emission.
De Broglie wavelength, and the evidence for it: λ = h/p = h/mv. Electrons passing through a thin graphite film produce diffraction rings, and diffraction is a wave property.
Why are line spectra discrete?: Electron energy levels are discrete, so only photons with energy hf = E₂ − E₁ can be emitted or absorbed.
Intensity: Power per unit area: I = P/A.
Current in terms of charge carriers: I = Q/t, and I = nAvq: number density × cross-sectional area × drift velocity × charge on each carrier.
Why does a thinner section of wire heat up more, for the same current?: From I = nAvq, a smaller area A needs a larger drift velocity v, so electrons collide more often with the lattice and transfer more energy there.
Resistivity, and how it differs from resistance: R = ρL/A. Resistivity ρ (Ω m) is a property of the material; resistance R is a property of the specimen.
Three expressions for electrical power: P = VI = I²R = V²/R
Filament lamp I–V characteristic: A curve that flattens: as the current rises the temperature rises, lattice vibrations increase and the resistance rises.
Diode I–V characteristic: Almost no current until about 0.6 V in forward bias, then a sharp rise; effectively no current in reverse.
Why does the resistance of an NTC thermistor fall as it gets hotter?: Heating releases more charge carriers, and this outweighs the increased lattice vibration.
Kirchhoff’s first law: The current into a junction equals the current out. A consequence of conservation of charge.
Kirchhoff’s second law: Around any closed loop, the sum of the e.m.f.s equals the sum of the p.d.s. A consequence of conservation of energy.
Resistors in series and in parallel: Series: R = R₁ + R₂ Parallel: 1/R = 1/R₁ + 1/R₂
E.m.f. vs potential difference: E.m.f.: energy supplied to each coulomb of charge by the source. P.d.: energy transferred from each coulomb of charge in a component.
Internal resistance equation, and the graph used in Core Practical 8: E = I(R + r), so V = E − Ir. A graph of terminal p.d. V against current I has gradient −r and intercept E.
A cell (e.m.f. 6.0 V, r = 0.50 Ω) drives a 5.5 Ω resistor. Current and terminal p.d.?: I = 6.0 ÷ 6.0 = 1.0 A V = 6.0 − 1.0 × 0.50 = 5.5 V
Potential divider output: V_out = V_in × R₂ / (R₁ + R₂). Using a thermistor or LDR as one resistor makes the output depend on temperature or light.
Core Practical 7: Determine the resistivity of a material: measure length and diameter (micrometer) and use the gradient of a graph of R against length (or against l/A).

Topic 3: Practical Skills in Physics I

Resolution of a metre rule, Vernier calipers and a micrometer screw gauge: Metre rule: 1 mm. Vernier calipers: 0.1 mm. Micrometer: 0.01 mm.
Uncertainty in a single reading: Half the resolution of the instrument (for example ±0.5 mm on a metre rule).
Correcting a zero error: A zero error is systematic: every reading is shifted by the same amount. Subtract a positive zero error; add the size of a negative one. Repeating does not remove it.
How should safety be written in a plan?: As a pair: the specific hazard and its precaution (for example, a falling mass: a sand tray and feet kept clear).
When are repeat readings useful, and when not?: Useful where there is random scatter (hand timing, a wire’s diameter). Not useful for a zero error or a digital reading that does not change.
Controls in a plan for resistance against length of a wire: Same wire (material and diameter), low current, short switch-on time, so the temperature stays the same.
Micrometer: sleeve 2.0 mm, thimble 45, zero error +0.03 mm. Reading?: 2.0 + 0.45 = 2.45 mm; 2.45 − 0.03 = 2.42 mm
Reading Vernier calipers: Main-scale reading before the Vernier zero + 0.1 mm × the number of the Vernier mark that lines up. For example 32 mm and the seventh mark: 32.7 mm.
Four things to check in another student’s results: Number of readings (at least six for a graph), range, significant figures matching the instrument’s resolution, and any inconsistent readings.
Improvements to avoid parallax and misreadings: A set square to keep a rule vertical; a pointer or fiducial marker and eye level with the scale; a micrometer instead of a ruler for a thin wire.
What should you do with an inconsistent reading?: Check it against the trend, re-measure and repeat. Do not simply delete it.
Uncertainty from repeated readings, and percentage uncertainty: Half the range: (largest − smallest) ÷ 2. Percentage uncertainty = uncertainty ÷ value × 100%.
Times of 3.2 s, 3.4 s and 3.3 s. Mean and percentage uncertainty?: Mean 3.3 s, half range 0.1 s, so 0.1 ÷ 3.3 × 100 = 3.0%
Random vs systematic error: Random: readings scatter either side of the true value; repeating and averaging reduces it. Systematic: every reading is shifted the same way; repeating does not remove it.
Precise vs accurate: Precise: repeated readings agree closely. Accurate: close to the true value.
How should you find a gradient from a graph?: Draw a large triangle on the best-fit line using two points far apart that are not data points, and give the gradient a unit.
A straight line that should pass through the origin has an intercept. What does it suggest?: A systematic error (such as a zero error) in one of the measurements.
Graph of R against L for a wire has gradient 7.3 Ω m⁻¹; the wire’s area is 7.07 × 10⁻⁸ m². Resistivity?: Gradient = ρ/A, so ρ = 7.3 × 7.07 × 10⁻⁸ = 5.2 × 10⁻⁷ Ω m

Topic 4: Further Mechanics, Fields and Particles

How is momentum conserved in a two-dimensional collision?: Momentum is a vector, so it is conserved separately in each of two perpendicular directions. Resolve, apply conservation to each, then recombine.
Kinetic energy in terms of momentum: Ek = p²/2m
0.15 kg at 8.0 m/s hits a stationary 0.25 kg ball and rebounds at 2.0 m/s. Velocity of the second ball?: 1.2 = −0.30 + 0.25v, so v = 6.0 m/s. KE before 4.8 J, after 0.3 + 4.5 = 4.8 J, so the collision is elastic.
Angular velocity: ω = θ/t = 2π/T = 2πf, in rad s⁻¹. Angles must be in radians. v = rω.
Centripetal acceleration and centripetal force: a = v²/r = rω² F = mv²/r = mrω²
Is centripetal force a separate force?: No. It is the resultant of the real forces present (tension, gravity, friction, normal contact or magnetic force), directed towards the centre.
Why does an object in uniform circular motion accelerate but keep the same kinetic energy?: Its direction, and so its velocity, changes continuously. The resultant force is perpendicular to the velocity, so it does no work.
Minimum speed at the top of a vertical circle on a string: When the tension is zero, gravity alone provides the centripetal force: mg = mv²/r, so v = √(gr).
Core Practicals 9 and 10: 9: investigate the relationship between force and change of momentum. 10: use ICT (such as video analysis) to analyse collisions between small spheres.
Impulse (Newton's second law in Unit 4): Impulse = FΔt = Δp, in N s (equal to kg m s⁻¹). It is the area under a force–time graph. Example: a 0.16 kg ball hit from rest to 45 m s⁻¹ receives an impulse of 0.16 × 45 = 7.2 N s.
Electric field strength: E = F/Q: force per unit positive charge (N C⁻¹ or V m⁻¹). Field lines run from positive to negative.
Coulomb’s law, and the radial field of a point charge: F = Q₁Q₂ / (4πε₀r²) E = Q / (4πε₀r²): an inverse-square field.
Field between parallel plates: Uniform: E = V/d, the same everywhere between the plates.
Electric potential of a point charge, and equipotentials: V = Q / (4πε₀r). Equipotentials are always perpendicular to field lines.
Path of a charged particle entering a uniform field at right angles: electric vs magnetic: Electric field: a parabola (constant force in a fixed direction, like a projectile). Magnetic field: a circle (force always perpendicular to the velocity).
Radius of a charged particle’s circular path in a magnetic field: BQv = mv²/r, so r = mv/BQ = p/BQ.
Capacitance, and energy stored by a capacitor: C = Q/V W = ½QV = ½CV² = Q²/2C (the area under a Q–V graph).
Capacitor discharge equation and time constant: Q = Q₀ e^(−t/RC). Time constant RC: after one time constant the charge has fallen to about 37% of its initial value.
A 220 μF capacitor at 9.0 V discharges through 47 kΩ. Time constant, and p.d. after it?: RC = 220 × 10⁻⁶ × 47 × 10³ = 10.3 s V = 9.0 × e⁻¹ = 3.3 V
Force on a current-carrying conductor and on a moving charge in a magnetic field: F = BIl sin θ F = BQv sin θ Zero when parallel to the field, maximum when perpendicular.
Magnetic flux and flux linkage: Flux φ = BA (Wb). Flux linkage = Nφ.
Faraday’s law and Lenz’s law: Faraday: the induced e.m.f. is proportional to the rate of change of flux linkage, ε = −d(Nφ)/dt. Lenz: the induced current opposes the change producing it (the minus sign), as conservation of energy requires.
Core Practical 11: Use an oscilloscope or data logger to display and analyse the p.d. across a capacitor as it charges and discharges through a resistor.
Quark composition of a proton and a neutron, with charges: Proton: uud, charge (+⅔) + (+⅔) + (−⅓) = +1. Neutron: udd, charge (+⅔) + (−⅓) + (−⅓) = 0.
Hadrons, baryons, mesons and leptons: Hadrons feel the strong force: baryons are three quarks; mesons are a quark and an antiquark. Leptons (electron, muon, tau and their neutrinos) are fundamental and do not feel the strong force.
Antiparticle: A particle with the same mass as its partner but with opposite properties such as charge.
What must be conserved in a particle interaction?: Charge, baryon number, lepton number, energy and momentum. To reject an interaction, name the rule it breaks.
Mass–energy, and the electronvolt: ΔE = c²Δm. 1 eV = 1.60 × 10⁻¹⁹ J, so 1 MeV = 1.60 × 10⁻¹³ J and 1 GeV = 1.60 × 10⁻¹⁰ J. Masses can be given in MeV/c².
Electron–positron annihilation at rest: The mass becomes two photons travelling in opposite directions (so momentum is conserved), each of energy 0.511 MeV.
Why are very high energies needed to probe the inside of nucleons?: Resolving very small distances needs a very short de Broglie wavelength, which means high momentum and so high energy. Kinetic energy can also become the mass of new particles.
How does a linear accelerator work?: An alternating p.d. across successive drift tubes is timed so the particle is accelerated at each gap. The tubes get longer because the particle is moving faster.
How does a cyclotron work?: Two dees in a magnetic field with an alternating p.d. across the gap. The field keeps the particle circling; it is accelerated at each crossing of the gap and its radius grows (r = mv/BQ).
What does a particle track in a magnetic field tell you?: The radius of curvature gives the momentum (r = p/BQ); the direction of curvature gives the sign of the charge.

Topic 5: Thermodynamics, Radiation, Oscillations and Cosmology

Internal energy: The sum of the randomly distributed kinetic and potential energies of the molecules in a system.
Why does the temperature stay constant while a substance melts or boils?: The energy supplied increases the potential energy of the molecules (their separation), not their kinetic energy, so the temperature does not change.
Specific heat capacity and specific latent heat equations: ΔE = mcΔθ: energy to raise 1 kg by 1 K is c. ΔE = LΔm: energy to change the state of 1 kg with no temperature change is L.
Energy to turn 0.50 kg of water at 100 °C into steam? (L = 2.26 × 10⁶ J/kg): E = 2.26 × 10⁶ × 0.50 = 1.13 × 10⁶ J
Absolute zero and the kelvin scale: T(K) = θ(°C) + 273. At absolute zero the molecules have minimum internal energy, not zero energy.
Ideal gas equations: pV = nRT (R = 8.31 J mol⁻¹ K⁻¹) pV = NkT (k = 1.38 × 10⁻²³ J K⁻¹) T in kelvin.
Kinetic theory: pressure, and mean molecular kinetic energy: pV = ⅓Nm⟨c²⟩ ½m⟨c²⟩ = (3/2)kT: mean molecular kinetic energy depends only on absolute temperature.
Assumptions of the kinetic model of an ideal gas: Many molecules in random motion; molecular volume negligible; no forces between molecules except in collisions; collisions elastic; collision time negligible compared with time between collisions.
Why is the internal energy of an ideal gas only kinetic?: There are no intermolecular forces, so there is no molecular potential energy. The internal energy depends only on temperature.
Core Practicals 12, 13 and 14: 12: calibrate a thermistor in a potential divider as a thermostat. 13: determine a specific latent heat. 14: pressure and volume of a fixed mass of gas at constant temperature.
Alpha radiation: A helium nucleus, charge +2. Stopped by paper. Strongly ionising.
Beta-minus radiation: An electron, charge −1. Stopped by about 3 mm of aluminium. Moderately ionising.
Gamma radiation: An electromagnetic photon, no charge. Reduced by thick lead. Weakly ionising.
Why is alpha the least penetrating radiation?: It is the most strongly ionising, so it loses its energy quickly and travels only a short distance.
Mass deficit and binding energy: Mass deficit: the mass of the separated nucleons minus the mass of the nucleus. The binding energy is ΔE = c²Δm. 1 u = 1.66 × 10⁻²⁷ kg.
Why do both fission and fusion release energy?: Binding energy per nucleon peaks around iron. Fusing light nuclei and splitting heavy nuclei both move towards higher binding energy per nucleon.
Beta-minus and beta-plus decay in terms of nucleons: β⁻: n → p + e⁻ + antineutrino (A same, Z + 1). β⁺: p → n + e⁺ + neutrino (A same, Z − 1).
Activity and the decay constant: A = λN (Bq). λ is the probability per unit time that a nucleus decays. N = N₀e^(−λt), and t½ = ln 2 / λ.
How do you find λ from activity measurements?: Subtract background, then plot ln A against t: a straight line of gradient −λ.
Core Practical 15: Investigate the absorption of gamma radiation by lead (count rate against absorber thickness, background subtracted).
Definition of simple harmonic motion: Acceleration is proportional to the displacement from the equilibrium position and always directed towards it: a = −ω²x. The restoring force F = −kx.
Maximum speed and maximum acceleration in SHM: v_max = ωA, at the equilibrium position. a_max = ω²A, at maximum displacement. ω = 2πf = 2π/T.
Periods of a simple pendulum and of a mass on a spring: Pendulum: T = 2π√(l/g) (small angles only). Mass–spring: T = 2π√(m/k). Neither depends on the amplitude.
A 0.60 kg mass oscillates on a spring of k = 15 N/m. Period?: T = 2π√(0.60/15) = 2π × 0.20 = 1.26 s
Phase of velocity relative to displacement in SHM: Velocity leads displacement by 90°: it is maximum at zero displacement and zero at maximum displacement.
Phase of acceleration relative to displacement in SHM: Acceleration is 180° out of phase with displacement: maximum and opposite at the extremes, zero at the centre.
Light damping: The amplitude decays gradually over many oscillations.
Critical damping: The fastest return to equilibrium without overshooting (used in car suspension). Heavy damping returns more slowly, also without oscillating.
Free vs forced oscillation, and resonance: Free: at the natural frequency with no driving force. Forced: driven by an external periodic force. Resonance: driving frequency = natural frequency, giving maximum amplitude.
Effect of more damping on a resonance curve: Lower peak amplitude, a broader curve, and the peak shifts slightly to a lower frequency.
Newton’s law of gravitation, and the field of a point mass: F = Gm₁m₂/r² g = F/m = Gm/r²
Gravitational potential of a point mass: V = −Gm/r. Always negative, rising to zero at infinity (unlike electric potential, which can be positive).
Luminosity vs radiant flux: Luminosity L: total power emitted by a star. Radiant flux F: power received per unit area, F = L / (4πd²).
Standard candle, with an example: An object of known luminosity, so measuring its flux gives its distance. Type Ia supernovae have a consistent peak luminosity.
Trigonometric parallax: The apparent shift of a nearby star against distant background stars as the Earth orbits the Sun, used to find its distance.
Wien’s law and the Stefan–Boltzmann law: λmax T = 2.898 × 10⁻³ m K L = 4πr²σT⁴ Use Wien for temperature first, then Stefan for radius.
A star has surface temperature 5800 K. Peak wavelength?: λmax = 2.898 × 10⁻³ ÷ 5800 = 5.00 × 10⁻⁷ m (500 nm)
Hertzsprung–Russell diagram: axes and regions: Luminosity (up) against temperature (increasing to the left). Main sequence: diagonal band. Red giants: top right (cool, luminous, so large). White dwarfs: bottom left (hot, dim, so small).
Evolution of a Sun-like star and of a massive star: Sun-like: main sequence → red giant → planetary nebula → white dwarf. Massive: main sequence → red supergiant → supernova → neutron star or black hole.
Doppler red-shift equation, and the age of the universe: z = Δλ/λ ≈ v/c. Hubble’s law v = H₀d gives an age of about 1/H₀.
Why is there controversy about the age and fate of the universe?: The value of the Hubble constant is uncertain, and the possible existence of dark matter (from galactic rotation curves) and dark energy affects how the expansion changes.

Topic 6: Practical Skills in Physics II

The seven things a Unit 6 plan is assessed on: Apparatus, calibration, measuring, control of variables, repeats, safety, and use of the data.
Why time 20 oscillations rather than one?: A reaction time of about 0.2 s is about 20% of a 1 s period but about 0.5% of a 40 s total, so the percentage uncertainty is much smaller.
A plan to test y = kxⁿ: what graph should be plotted?: lg y against lg x. The gradient is n and the intercept is lg k.
A plan to test y = A e^(bx): what graph should be plotted?: ln y against x. The gradient is b and the intercept is ln A.
How should calibration be stated in a plan?: A zero check on each instrument, or a comparison with a known value, before readings are taken.
Improvements to timing an oscillation: Use a fiducial marker at the equilibrium position for a consistent start and stop, and time more oscillations to cut the reaction-time percentage.
Number and range of readings: At least six readings, over a wide, evenly spaced range. A narrow range gives a poor gradient.
Significant figures in a table of raw readings: Keep the instrument’s resolution, with trailing zeros, and the same number of decimal places down a column.
How is the heading of a logged column written?: With the unit inside the bracket, for example lg (L / m) or ln (V / V). The logarithm itself has no unit.
A reading lies off the line. What should you do?: Re-read and repeat it, and compare with the value the line predicts. Keep it if the repeat is still off the line, because the physics may change there.
Repeatability vs reproducibility: Repeatability: precision with one operator, one method and a short timescale. Reproducibility: precision when different operators or apparatus are used.
Combining uncertainties: Add or subtract quantities: add absolute uncertainties. Multiply or divide: add percentage uncertainties. Raise to a power n: multiply the percentage uncertainty by n.
m = 0.240 ± 0.002 kg, v = 3.40 ± 0.05 m s⁻¹. Kinetic energy and its uncertainty?: KE = ½ × 0.240 × 3.40² = 1.39 J % = 0.83% + 2 × 1.5% = 3.8% KE = 1.39 ± 0.05 J
A lg T against lg L graph has gradient 0.50. What does this show?: T ∝ L^0.50: the period is proportional to the square root of the length.
How do you judge whether a result is accurate?: Find the range allowed by its uncertainty: if the accepted value lies inside it, the result is accurate within the uncertainty. Without an uncertainty, use percentage difference = (measured − accepted) ÷ accepted × 100%.
Error (in measurement): The difference between a result and the true value. It is not a mistake by the operator.
Valid measurement: A measurement that measures what it is meant to measure.

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Written for Pearson Edexcel International Advanced Level in Physics (YPH11), syllabus YPH11 (Issue 3).

Cards by Marlbridge Academic Team; 16 restate definitions from the YPH11 revision notes. This deck was reviewed by Hassan on 2026-11-05. Report an error.

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