Numbers
AQA AS-Level Physics 7408
Measurements and Their Errors
Particles and Radiation
Topic overviewConstituents of the atomStable and unstable nucleiParticles, antiparticles and photonsParticle interactionsClassification of particlesQuarks and antiquarksApplications of conservation lawsThe photoelectric effectCollisions of electrons with atomsEnergy levels and photon emissionWave-particle duality
Waves
Mechanics and Materials
Electricity
- 6 subtopics
- 27 things to know
- Papers 1 and 3
What Electricity covers
Electricity is examined on Papers 1 and 3. It covers current, potential difference and resistance, the characteristics of common components, circuit rules, and what internal resistance does to a real source.
Where it is assessed
Papers 1 and 3
Core content, then practical skills and data analysis.
Check the AQA specification ↗The 6 subtopics
Each one has its own page. AQA AS Physics students sit this topic in the first year.
- Basics of electricityCurrent as rate of flow of charge, potential difference as work per unit charge, and resistance.Open →
- Current–voltage characteristicsOhm's law and the characteristics of a resistor, a filament lamp and a diode.Open →
- ResistivityThe resistivity equation, the effect of temperature on a metal, and superconductivity.Open →
- CircuitsResistors in series and parallel, the circuit rules, and the equations for electrical power.Open →
- Potential dividerThe potential divider equation, and using an LDR or thermistor to make a sensing circuit.Open →
- Electromotive force and internal resistanceEmf, terminal potential difference, lost volts, and measuring both experimentally.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Numbers
Define potential difference, give its defining equation, and state what one volt equals.
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What does W stand for in V = W/Q, and how is resistance defined?
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Why does a filament lamp's resistance rise with current, and what does Ohm's law state?
Process
What shape is the characteristic for a filament lamp, and how does a diode behave?
Numbers
Does Ohm's law apply to all electrical components, and why?
Key term
On which axis can current be plotted when drawing a current–voltage characteristic?
Numbers
How is resistivity defined, what do its symbols mean, and what is its unit?
Process
Why does the resistance of a metal rise with temperature?
Key term
What are superconductors used for, and does critical temperature vary between materials?
Key term
Which instrument is used to measure the diameter of a wire when determining its resistivity?
Numbers
How is total resistance found in series, and how is electrical power calculated?
Numbers
When would you use P = I²R rather than P = V²/R, and what is true of current in series?
Numbers
Why is current the same everywhere in series, and how do the potential differences add?
Numbers
What happens to emf and current capability when identical cells are connected in parallel?
Numbers
Explain why the sum of potential differences around a closed loop must equal the total emf
Key term
Explain why an ammeter is connected in series rather than in parallel
Numbers
What is the potential divider equation, and why is the current the same through each resistor?
Numbers
What does the potential divider equation assume, and what do the resistor values affect?
Process
How do an LDR and a thermistor behave in a potential divider?
Key term
How can a potential divider be made to supply a variable potential difference?
Numbers
What is emf, how is it defined by energy and charge, and what unit is it in?
Numbers
How is the volt expressed in joules and coulombs, and what is internal resistance?
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What is terminal potential difference, and how does it relate to emf?
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Why is terminal potential difference less than emf, and when are they equal?
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What are lost volts, and how are they calculated?
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How is current found in a circuit with internal resistance, and how is emf measured?
Take Electricity further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Potential difference vs Electromotive force
Potential difference: the work done per unit charge in moving a charge between two points. Electromotive force: the energy transferred per unit charge by a source in driving charge around a complete circuit.
Resistance vs Resistivity
Resistance: potential difference divided by current. Resistivity: material property linking opposition to current with conductor geometry.
Series circuit vs Parallel circuit
Series circuit: components share one current path. Parallel circuit: components connect across common potential difference.
Questions from this topic
Each one with the model answer underneath.
- 1
What is the definition of electric current?
Model answer
Electric current is the rate of flow of charge.
- 2
State the formula that relates current, charge and time.
Model answer
I = ΔQ/Δt, where I is current in amperes, ΔQ is charge in coulombs, and Δt is time in seconds.
- 3
In the equation I = ΔQ/Δt, what does the symbol ΔQ represent and what is its SI unit?
Model answer
ΔQ represents the charge that flows, measured in coulombs (C).
- 4
What quantity does the equation I = ΔQ/Δt allow you to determine when charge flow and time interval are known?
Model answer
It allows you to calculate the electric current.
- 5
Calculate the current when charge = 62 C, time = 11 s.
Model answer
Current = 62 ÷ 11 = 5.64 A.
- 6
Define potential difference.
Model answer
Potential difference is the work done per unit charge.
What is inside Levo
Six ways to work the same material.
Electricity revision questions
- Is Electricity examined at AS in AQA Physics?
- Yes. It sits in Papers 1 and 3, 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 Electricity cover in AQA AS-Level Physics?
- 6 subtopics: basics of electricity, current–voltage characteristics, resistivity, circuits, potential divider and electromotive force and internal resistance. Each one has its own page with questions and model answers.
- How is Electricity organised?
- By the AQA 7408 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Electricity, 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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