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
Current, Charge and Potential Difference
Electric current and the coulomb
- 3 things to know
- Unit AS 1
Overview
Electric current, equation relating current, charge and time and charge carriers in a metallic conductor.
What you need to know
Answer each one before you reveal it.
Your recallNot started
Numbers
In 4.0 s, 6.0 × 10¹⁸ electrons pass a point in a wire. Calculate the current, taking the elementary charge as 1.60 × 10⁻¹⁹ C.
Key term
Define electric current.
Questions from this subtopic
Each one with the model answer underneath.
- 1
Define electric current.
Model answer
Electric current is the rate of flow of electric charge past a point in a circuit.
- 2
State the equation relating current, charge and time, and define every symbol with its unit.
Model answer
The equation is I = Q/t, where I is the current in amperes, Q the charge that passes in coulombs and t the time taken in seconds.
- 3
Define the coulomb.
Model answer
One coulomb is the charge that passes a point when a steady current of one ampere flows for one second, so 1 C = 1 A s.
- 4
Write the equation I = Q/t in the form used to find the charge that has passed.
Model answer
The rearranged form is Q = It, so the charge in coulombs is the current in amperes multiplied by the time in seconds.
- 5
A steady current of 0.25 A flows for 2.0 minutes. Calculate the charge that passes.
Model answer
The charge is Q = It = 0.25 × 120 = 30 C, and 30 C ÷ 120 s returns the current of 0.25 A as a check.
- 6
A charge of 4500 C passes through a circuit in 15 minutes. Calculate the current.
Model answer
The current is I = Q/t = 4500 ÷ 900 = 5.0 A, and 5.0 A × 900 s gives back 4500 C as a check.
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