Electricity and magnetism

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Sample objectives

What this unit covers

• Simple phenomena of magnetism: Explain the interactions between magnetic poles and between magnets and magnetic materials, using terms like north pole, south pole, attraction, repulsion, magnetised, and unmagnetised.
• Simple phenomena of magnetism: Explain the concept of induced magnetism.
• Electric charge: Identify that there are two types of electric charges: positive and negative.
• Electric charge: Recognize that like charges repel each other while opposite charges attract.
• Electric current: Understand that electric current is associated with the movement of electric charge.
• Electric current: Explain how ammeters, both analogue and digital, are used across various measurement ranges.
• Electromotive force and potential difference: Explain electromotive force (e.m.f.) as the amount of electrical work performed by a source to move a unit charge around a full circuit.
• Electromotive force and potential difference: Understand that electromotive force (e.m.f.) is quantified in volts (V).
• Resistance: Remember and apply the formula for resistance, which is V = I × R.
• Resistance: Explain how to conduct an experiment to measure resistance using a voltmeter and an ammeter, including the necessary calculations.
• Electrical energy and electrical power: Recognize that electric circuits convey energy from a source of electrical energy, like a battery or mains supply, to the components of the circuit and subsequently to the environment.
• Electrical energy and electrical power: Memorize and apply the formula for electrical power, expressed as P = V I.
• Circuit diagrams and circuit components: Create and understand circuit diagrams that include cells, batteries, power supplies, generators, potential dividers, switches, resistors (both fixed and variable), heaters, thermistors (only NTC), light-dependent resistors (LDRs), lamps, motors, bells, ammeters, voltmeters, magnetising coils, transformers, fuses, and relays, and be aware of the behavior of these components within a circuit.
• Circuit diagrams and circuit components: Create and understand circuit diagrams that include diodes and light-emitting diodes (LEDs), and be aware of how these components function within a circuit.
• Series and parallel circuits: Understand that the electric current is uniform at all points within a series circuit.
• Series and parallel circuits: Learn how to build and utilize both series and parallel circuits.
• Action and use of circuit components: Understand that the potential difference across a conductor increases with its resistance when the current remains constant.
• Action and use of circuit components: Explain how a variable potential divider operates.
• Electrical safety: Identify the dangers associated with: (a) damaged insulation (b) overheating cables (c) wet conditions (d) excessive current due to overloading plugs, extension leads, and sockets when using mains electricity.
• Electrical safety: Understand that a mains circuit includes a live wire, a neutral wire, and an earth wire, and describe why the switch should be connected to the live wire to safely turn off the circuit.
• Electromagnetic induction: Understand that moving a conductor through a magnetic field or having a changing magnetic field around a conductor can create an electromotive force (e.m.f.) in that conductor.
• Electromagnetic induction: Explain how to conduct an experiment that shows the principle of electromagnetic induction.
• The a.c. generator: Explain the basic design of an alternating current (a.c.) generator, including the roles of a rotating coil or magnet, and the function of slip rings and brushes when applicable.
• The a.c. generator: Draw and analyze graphs showing the relationship between electromotive force (e.m.f.) and time for basic a.c. generators, and connect the orientation of the generator coil to the e.m.f. peaks, troughs, and zero points.
• Magnetic effect of a current: Explain the arrangement and orientation of the magnetic field created by currents flowing through straight wires and solenoids.
• Magnetic effect of a current: Outline a procedure to demonstrate the magnetic field pattern (including its direction) produced by currents in straight wires and solenoids.
• Force on a current-carrying conductor: Outline an experiment demonstrating that a force is exerted on a conductor carrying current within a magnetic field, including how reversing (a) the current and (b) the magnetic field direction affects the force.
• Force on a current-carrying conductor: Identify and apply the relative directions of force, magnetic field, and current.
• The d.c. motor: Understand that a coil carrying an electric current within a magnetic field can experience a rotational force, which can be enhanced by increasing: (a) the number of coil turns (b) the electric current (c) the magnetic field strength
• The d.c. motor: Explain how an electric motor functions, detailing the role of the split-ring commutator and brushes in its operation
• The transformer: Explain how a basic transformer is built, highlighting the use of a soft-iron core for changing voltage levels.
• The transformer: Identify and define the roles of primary and secondary coils, as well as the concepts of step-up and step-down transformers.