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
Electric Fields
Coulomb's law
- 3 things to know
- Unit A2 2
Overview
Recall questions on the statement of the law and the equation in both its ε₀ and k forms with the values of both constants, what the sign of the answer means, the inverse square behaviour, worked force calculations for laboratory charges and for the hydrogen atom, and when a charged sphere may be treated as a point charge.
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
Give the value and unit of the permittivity of free space.
Key term
How is Coulomb's law written using the constant k?
Questions from this subtopic
Each one with the model answer underneath.
- 1
State Coulomb's law.
Model answer
The force between two point charges is proportional to the product of the charges and inversely proportional to the square of the distance between them.
- 2
Give the equation for the force between two point charges and define each symbol.
Model answer
F = q₁q₂/(4πε₀r²), where F is the force in newtons, q₁ and q₂ the charges in coulombs, r their separation in metres and ε₀ the permittivity of free space.
- 3
Give the value and unit of the permittivity of free space.
Model answer
ε₀ is 8.85 × 10⁻¹² F m⁻¹.
- 4
How is Coulomb's law written using the constant k?
Model answer
F = kq₁q₂/r², where k is equal to 1/(4πε₀).
- 5
Calculate the value of k from ε₀.
Model answer
k = 1 ÷ (4π × 8.85 × 10⁻¹²) = 1 ÷ 1.112 × 10⁻¹⁰, which is 8.99 × 10⁹ N m² C⁻².
- 6
What does a positive value of the force calculated from Coulomb's law indicate?
Model answer
That the force is repulsive, which happens when the two charges have the same sign.
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