Key term
CCEA AS-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
Current, Charge and Potential Difference
- 5 subtopics
- 15 things to know
- Unit AS 1
What Current, Charge and Potential Difference covers
Current, Charge and Potential Difference is examined in Unit AS 1, Forces, Energy and Electricity, and drawn on again in Unit AS 3, Practical Techniques and Data Analysis. It covers electric current and the coulomb, potential difference and energy transfer, potential difference, power and current, electromotive force and comparing electromotive force and potential difference.
Where it is assessed
Unit AS 1
Forces, Energy and Electricity, and again in Unit AS 3, Practical Techniques and Data Analysis.
Check the CCEA specification ↗The 5 subtopics
Each one has its own page. CCEA AS Physics students sit this topic in the first year.
- Electric current and the coulombElectric current, equation relating current, charge and time and charge carriers in a metallic conductor.Open →
- Potential difference and energy transferPotential difference between two points in a circuit, equation relating potential difference, energy and charge and volt in terms of energy and charge.Open →
- Potential difference, power and currentEquation relating potential difference to power and current and volt in terms of power and current.Open →
- Electromotive forceRecall questions on the definition and the energy-per-unit-charge equation, why the name is misleading, four sources and the energy conversion each performs, cells in series and in opposition, cells in parallel, what a high-resistance voltmeter reads on an open circuit, and calculations of energy transferred.Open →
- Comparing electromotive force and potential differenceRecall questions on the essential difference between the two, why both are measured in volts, where each is measured in a circuit, why terminal potential difference is less than the electromotive force and when the two are equal, and worked examples on a battery, a torch and a solar cell.Open →
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
State the equation relating potential difference, energy and charge, and define every symbol with its unit.
Key term
State the equation relating potential difference to power and current, and define every symbol with its unit.
Numbers
A motor operating at 12 V draws a current of 2.5 A for 5.0 minutes. Calculate the electrical energy supplied.
Key term
Show that the watt is equivalent to the volt ampere.
Key term
State the equation for electromotive force in terms of energy and charge, and give the unit.
Key term
Name four sources of electromotive force and state the energy conversion each carries out.
Numbers
A 1.5 V cell drives a steady current of 0.20 A for 30 minutes. Calculate the total energy it converts into electrical energy.
Key term
How does the electromotive force of a cell change as the cell is used, and why?
Key term
Define the potential difference between two points in a circuit.
Key term
State the essential difference between electromotive force and potential difference.
Key term
Define electric current.
Key term
Define the volt in terms of energy and charge.
Key term
Across which part of a circuit is an electromotive force measured, and across which part is a potential difference measured?
Take Current, Charge and Potential Difference further
The same content, four other ways.
Questions from this topic
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.
What is inside Levo
Six ways to work the same material.
Current, Charge and Potential Difference revision questions
- Is Current, Charge and Potential Difference examined at AS in CCEA Physics?
- Yes. It sits in Unit AS 1, which you take in the first year, so it is on the AS paper as well as counting towards the full A level.
- What does Current, Charge and Potential Difference cover in CCEA AS-Level Physics?
- 5 subtopics: electric current and the coulomb, potential difference and energy transfer, potential difference, power and current, electromotive force and comparing electromotive force and potential difference. Each one has its own page with questions and model answers.
- How is Current, Charge and Potential Difference organised?
- By the CCEA 1210 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Current, Charge and Potential Difference, 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.
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