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
Charged Particles and Accelerators
Circular paths in a magnetic field
- 3 things to know
- Unit A2 2
Overview
Recall questions on the magnetic force as the centripetal force, the derivation of r = mv/(Bq) with every symbol, the effect of doubling the speed or the flux density, worked radius calculations for an electron, why the charge to mass ratio decides the radius, the period T = 2πm/(Bq) and why it does not depend on speed.
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
What provides the centripetal force when a charged particle moves in a circle in a magnetic field?
Key term
How does the radius of a charged particle's circular path in a magnetic field change if its speed is doubled?
Questions from this subtopic
Each one with the model answer underneath.
- 1
What provides the centripetal force when a charged particle moves in a circle in a magnetic field?
Model answer
The magnetic force Bqv, which always points towards the centre of the circular path.
- 2
Derive the equation for the radius of the circular path.
Model answer
Setting Bqv equal to mv²/r and cancelling one factor of v gives r = mv/(Bq).
- 3
Define each symbol in r = mv/(Bq).
Model answer
r is the radius in metres, m the mass in kilograms, v the speed in m s⁻¹, B the flux density in tesla and q the charge in coulombs.
- 4
How does the radius change if the particle's speed is doubled?
Model answer
The radius doubles, since radius is proportional to speed at fixed field and charge to mass ratio.
- 5
How does the radius change if the flux density is doubled?
Model answer
The radius halves, since radius is inversely proportional to the flux density.
- 6
Calculate the radius of the path of an electron travelling at 2.0 × 10⁷ m s⁻¹ in a field of 0.050 T.
Model answer
r = mv/(Bq) = 9.11 × 10⁻³¹ × 2.0 × 10⁷ ÷ (0.050 × 1.60 × 10⁻¹⁹) = 1.82 × 10⁻²³ ÷ 8.0 × 10⁻²¹, which is 2.3 × 10⁻³ m.
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 Charged Particles and Accelerators, 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.