Electricity and Magnetism

Worked examples (12)extended set

• 1Sorting bars into magnets, magnetic and non-magnetic materials
• 2Soft iron near each pole (multiple choice)
• 3Magnetic separation of steel and aluminium cans
• 4Soft iron or steel? Temporary and permanent magnets
• 5Poles and field strength from a two-magnet field pattern
• 6Which pole, and where is the field strongest? (multiple choice)
• 7Plotting a field line with a compass
• 8Finding the poles of an unlabelled magnet with compasses
• 9Paper-clip experiment: soft iron and steel
• 10Permanent magnet or electromagnet?
• 11Field between unlike poles: strength and forces
• 12Which bar is the magnet? (no other equipment)

Model answers (6)

• ✓Model answer — Paper 2/4 short-answer style
• ✓Model answer — Paper 2/4 style
• ✓Model answer — Paper 4 explanation style
• ✓Model answer — Paper 4 structured style
• ✓Model answer — Paper 4 / Paper 6 style
• ✓Model answer — Paper 4 extended-response style

Worked examples (12)extended set

• 1Charging a plastic strip by friction
• 2Which unit is the volt? (multiple choice)
• 3Charging a phone: charge and energy
• 4Electric fields: plates, a dust particle and a charged sphere
• 5Resistance, length and diameter (multiple choice)
• 6Current–voltage graphs: resistor, lamp and diode
• 7Resistance from analogue meter readings
• 8How resistance depends on length: analysing results
• 9Air fryer: current, kilowatt-hours and cost
• 10E.m.f., p.d. and energy in a torch circuit
• 11Designing a heating element
• 12Charging two metal spheres without touching them

Model answers (6)

• ✓Model answer — Paper 2/4 short-answer style
• ✓Model answer — Paper 2/4 style
• ✓Model answer — Paper 4 structured style
• ✓Model answer — Paper 4 structured style
• ✓Model answer — Paper 4 explanation style
• ✓Model answer — Paper 4 multi-part structured style

Worked examples (12)extended set

• 1Naming components and predicting a thermistor's effect
• 2Cells in series, one the wrong way round
• 3Diodes and an LED in parallel branches (multiple choice)
• 4Fan heater: currents in parallel branches
• 5Meter readings in a series–parallel circuit
• 6Finding an unknown resistor from the ammeter reading
• 7Thermistor in series: resistance from a milliammeter reading
• 8LDR potential divider: a light-activated drawer alarm
• 9Potential divider ratio (multiple choice)
• 10Testing identical resistors in series and in parallel
• 11What happens when one lamp in a network fails?
• 12Thermistor fan switch: reading the temperature from a graph

Model answers (6)

• ✓Model answer — Paper 2/4 short-answer style
• ✓Model answer — Paper 2/4 style
• ✓Model answer — Paper 4 structured style
• ✓Model answer — Paper 4 structured style
• ✓Model answer — Paper 4 application style
• ✓Model answer — Paper 4 multi-part structured style

Worked examples (12)extended set

• 1Naming the hazard in four household situations
• 2Where the fuse and the switch go
• 3Why the switch must be in the live wire
• 4How the earth wire and fuse protect the user
• 5Choosing a fuse for a two-element heater
• 6What the fuse does in a double-insulated appliance
• 7Setting a trip switch for a kitchen circuit
• 8Is this extension lead overloaded?
• 9Why damp conditions are dangerous
• 10Heating in an extension cable
• 11Spot the three wiring faults
• 12Investigating fuse wire

Model answers (6)

• ✓Model answer — Paper 2/4 short-answer style
• ✓Model answer — Paper 2/4 style
• ✓Model answer — Paper 4 explanation style
• ✓Model answer — Paper 4 structured style
• ✓Model answer — Paper 4 application style
• ✓Model answer — Paper 4 multi-part structured style

Worked examples (12)extended set

• 1The magnetic field around a straight wire
• 2Demonstrating electromagnetic induction
• 3Which pole is induced? Opposing the change
• 4Which way must the wire move?
• 5The rolling rod on rails
• 6Inside a d.c. motor
• 7The a.c. generator: rings, brushes and output
• 8A transformer for a welding set
• 9Step-up transformer: what happens to the current?
• 10Bending a beam of electrons
• 11Reading a generator's e.m.f.–time graph
• 12Power lost in a transmission line

Model answers (6)

• ✓Model answer — Paper 2/4 short-answer style
• ✓Model answer — Paper 2/4 style
• ✓Model answer — Paper 4 structured style
• ✓Model answer — Paper 4 structured style
• ✓Model answer — Paper 4 extended-explanation style
• ✓Model answer — Paper 4 extended-response style