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
Nuclear Energy, Fission and Fusion
Mass–energy equivalence and E = Δmc²
- 3 things to know
- Unit A2 1
Overview
What is meant by the equivalence of mass and energy, equation linking a change in mass to the energy released and value of the electronvolt in joules.
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
State the equation linking a change in mass to the energy released, and define every symbol.
Key term
State the value of the speed of light in a vacuum and the value of c².
Questions from this subtopic
Each one with the model answer underneath.
- 1
State what is meant by the equivalence of mass and energy.
Model answer
Mass and energy are two forms of the same thing, so any change in the energy of a system is accompanied by a proportional change in its mass, and mass can be converted into energy and energy into mass.
- 2
State the equation linking a change in mass to the energy released, and define every symbol.
Model answer
E = Δmc², where E is the energy in joules, Δm the change in mass in kilograms and c the speed of light in a vacuum, 3.00 × 10⁸ m s⁻¹.
- 3
State the value of the speed of light in a vacuum and the value of c².
Model answer
The speed of light in a vacuum is c = 3.00 × 10⁸ m s⁻¹, so c² = 9.00 × 10¹⁶ m² s⁻².
- 4
Why is only a very small mass needed to release a very large amount of energy?
Model answer
The conversion factor c² is 9.00 × 10¹⁶ m² s⁻², so even a mass of a milligram corresponds to an energy of about 10¹¹ J.
- 5
Calculate the energy released when a mass of 1.0 × 10⁻³ kg is completely converted into energy.
Model answer
E = Δmc² = 1.0 × 10⁻³ × 9.00 × 10¹⁶ = 9.0 × 10¹³ J.
- 6
Calculate the energy equivalent of one unified atomic mass unit in joules.
Model answer
E = Δmc² = 1.66 × 10⁻²⁷ × 9.00 × 10¹⁶ = 1.49 × 10⁻¹⁰ J.
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