Gravitational fields describe how masses interact at a distance through the force of gravity. A gravitational field is defined as the force per unit mass experienced by a small test mass placed in the field, allowing you to analyse gravity without needing direct contact between objects. In this topic you study field lines, field strength, and how gravitational forces vary with distance according to an inverse-square law. You also examine gravitational potential and the idea that work must be done to move a mass within a field. These concepts provide the framework for understanding orbits, planetary motion, and the behaviour of objects in both uniform and non-uniform gravitational fields.

Electric fields describe how electric charges exert forces on one another at a distance. An electric field is defined as the force per unit charge acting on a small positive test charge placed in the field, which allows you to analyse electrical interactions without direct contact. In this topic you study field lines, field strength, and the way electric forces vary with distance from point charges according to Coulomb’s law. You also examine electric potential, the work needed to move a charge within a field, and the differences between uniform fields (such as those between parallel plates) and radial fields around isolated charges. These ideas form the basis for understanding capacitors, charge distribution, and many electrostatic phenomena.

Magnetic fields describe the region around a magnet or moving charge where other magnets or currents experience a force. A magnetic field is represented by field lines that show its direction and relative strength, and it is quantified by the magnetic flux density B, measured in tesla. In this topic you examine how magnetic fields are produced by permanent magnets, by electric currents in wires or coils, and by moving charges. You also explore the force on a current-carrying conductor and on a charged particle moving through a field, using relationships such as F=Bqv and F = BIL.  These ideas are essential for understanding devices like electric motors, generators, transformers, and particle accelerators, all of which rely on predictable interactions between currents and magnetic fields. 

Electromagnetic induction describes how a changing magnetic field can produce an induced emf and, if the circuit is complete, an induced current. In this topic you study Faraday’s law, which states that the magnitude of the induced emf is proportional to the rate of change of magnetic flux, and Lenz’s law, which determines the direction of the induced current so that it opposes the change causing it. You examine how flux linkage changes in practical situations such as moving a conductor through a field, rotating coils in generators, or varying the current in nearby coils. These principles form the basis of key technologies including transformers, power generation, and many sensing devices, making induction one of the most applied parts of the A-level electricity and magnetism syllabus.