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Led by Michael Faraday Simulacrum
Six tutorials covering AQA GCSE Physics §4.2 Electricity — charge and current, resistance and Ohm's Law, series and parallel circuits, domestic AC supply and safety, power and the National Grid, and static electricity with electric fields — taught by simulacra of the physicists who built the subject from first principles.
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Led by André-Marie Ampère Simulacrum
The question
What is an electric current, and what does it mean to draw one on paper?
Territory
the need for a source of potential difference to drive a current · electric current as the rate of flow of charge · Q = It · why the current in a single closed loop is the same at every point · standard circuit diagram symbols · drawing and interpreting circuit diagrams
Outcome
The student can draw and interpret a circuit diagram using standard symbols, state the relationship between charge, current, and time, and apply Q = It in both directions. (AQA 4.2.1.1, 4.2.1.2)
Led by Georg Simon Ohm Simulacrum
The question
What determines how much current flows through a component for a given potential difference?
Territory
V = IR · the meaning of resistance · ohmic vs non-ohmic components · filament lamp (resistance rises with temperature) · diode (conducts one way only) · thermistor (resistance falls with rising temperature — used in thermostats) · light-dependent resistor (resistance falls with rising light intensity — used in dusk-sensing switches) · I–V characteristic curves · required practical 3 (factors affecting resistance — length of wire, combinations in series and parallel) · required practical 4 (I–V characteristics of filament lamp, diode, and fixed resistor)
Outcome
The student can apply V = IR, distinguish ohmic from non-ohmic behaviour, sketch and interpret I–V curves for the four components in the spec, carry out Required Practicals 3 and 4, and name practical applications of thermistors and LDRs. (AQA 4.2.1.3, 4.2.1.4)
Led by James Clerk Maxwell Simulacrum
The question
What happens to current, potential difference, and resistance when we connect components in series versus parallel?
Territory
series circuit rules (same current through each component, pd shared, R_total = R1 + R2) · parallel circuit rules (same pd across each component, currents sum, R_total less than smallest individual resistor) · why adding resistors in series increases total resistance · why adding resistors in parallel decreases total resistance · using circuit diagrams to construct and check both types · solving problems for series circuits with equivalent resistance · (note: calculation of total resistance for two parallel resistors is not required at GCSE)
Outcome
The student can state the rules for series and parallel circuits, explain qualitatively why they differ, construct both types from a diagram, and calculate currents, potential differences, and resistances in series circuits using the concept of equivalent resistance. (AQA 4.2.2)
Led by Nikola Tesla Simulacrum
The question
What actually comes out of a wall socket, and why is it genuinely dangerous?
Territory
direct current versus alternating current · the UK mains supply: 230 V, 50 Hz · three-core cable · colour codes (live = brown, neutral = blue, earth = green and yellow stripes) · the live wire carries the alternating pd from the supply · the neutral wire completes the circuit · the earth wire is a safety wire at 0 V that carries current only in a fault · the pd between live and earth is about 230 V · the neutral wire is close to earth potential · why a live wire is dangerous even when the switch is open · the danger of any connection between live and earth
Outcome
The student can distinguish direct from alternating pd, state the frequency and voltage of the UK mains supply, identify the three wires in a mains cable and their colour codes, and explain the safety role of the earth wire and the hazards of live-wire contact. (AQA 4.2.3.1, 4.2.3.2)
Led by Michael Faraday Simulacrum
The question
How is the energy you pay for on the electricity bill actually delivered — and why does it travel at hundreds of thousands of volts to arrive at 230?
Territory
P = VI · P = I²R · E = Pt · E = QV · worked examples from household appliances · kinetic energy devices (motors) and heating devices · why appliance energy use depends on both power rating and time on · the National Grid as a system of cables and transformers · step-up transformers at the power station · step-down transformers near consumers · why higher-voltage transmission is more efficient · (construction and operation of transformers is covered in full in Course 7, Magnetism and Electromagnetism)
Outcome
The student can apply all four power and energy equations, reason about appliance energy use from power ratings and time, and explain why the National Grid uses step-up and step-down transformers to transfer energy efficiently over distance. (AQA 4.2.4.1, 4.2.4.2, 4.2.4.3)
Led by Charles-Augustin de Coulomb Simulacrum
The question
Why does rubbing a balloon on your hair make it stick to a wall, and what is the invisible thing that connects a charged object to its surroundings?
Territory
triboelectric charging — rubbing insulators, electrons transferred, equal and opposite charges left behind · attraction and repulsion as non-contact forces · the production of sparks · the concept of an electric field as a region in which a second charge experiences a force · the field is strongest close to the charged object and weakens with distance · the force on a second charge gets stronger as the objects approach · drawing the electric field pattern for an isolated charged sphere · how the field concept explains electrostatic phenomena including sparking
Outcome
The student can describe the production of static electricity by triboelectric charging, explain attraction and repulsion of charges as non-contact forces, draw the electric field pattern around an isolated charged sphere, and use the field concept to explain electrostatic phenomena including sparking. (AQA 4.2.5.1, 4.2.5.2)