Coaching Centre
Module 4: Electricity and Magnetism Notes
Electric charge, fields and circuits, and the magnetic fields made by magnets and electric currents.
Sections
-
4A Electric charge and charging Mastered
Positive and negative charge, the elementary charge and quantisation, conservation of charge, conductors and insulators, charging by friction, conduction and induction, polarisation, and how a gold-leaf electroscope detects charge and tests its sign.
-
4B Electric fields Mastered
The electric field as force per unit charge (E = F/q), field direction and the test charge, rules for drawing field lines for point charges, dipoles and like charges, adding fields as vectors, and the uniform field between parallel plates (E = V/d).
-
4C Coulomb's law Mastered
The inverse square law for the force between point charges, k and the permittivity of free space, Newton's third law for charges, adding forces from several charges in one and two dimensions, the field of a point charge, and why electric forces dwarf gravity for charged particles.
-
4D Work, energy and potential difference Mastered
Work done on a charge by a uniform electric field, electric potential energy, potential difference as energy per unit charge (V = W/q), why E = V/d, equipotential lines, the electron volt, and the speed of a charge accelerated from rest.
-
4E Current and potential difference in circuits Mastered
Electric current as the rate of flow of charge (I = q/t), conventional current and electron flow, drift velocity and why it is so slow, emf and potential difference as energy per coulomb (V = W/q), and how to connect ammeters and voltmeters.
-
4F Resistance and I–V characteristics Mastered
Resistance as R = V/I, Ohm's law and ohmic conductors, how length, area, material (resistivity) and temperature affect resistance, the I–V characteristics of resistors, filament globes, diodes, LEDs and thermistors, and the mandatory Ohm's law investigation.
-
4G Series, parallel and Kirchhoff's laws Mastered
Kirchhoff's junction rule (conservation of charge) and loop rule (conservation of energy), deriving the rules for resistors in series and parallel, solving mixed series–parallel circuits step by step, the voltage divider, and an introduction to circuits with two sources.
-
4H Electrical power, energy and safety Mastered
Power as the rate of energy transfer (P = VI = I²R = V²/R), energy and the kilowatt-hour, why globes are dimmer in series, the 230 V household supply, active, neutral and earth wires, circuit breakers, RCDs, earth faults and the effects of current on the body.
-
4I Magnets and ferromagnetism Mastered
Magnetic poles and the forces between them, magnetic field lines and field strength in teslas, Earth's magnetic field, ferromagnetic materials and the domain model, induced magnetism, hard and soft magnetic materials, hysteresis and the Curie temperature.
-
4J Magnetic fields of currents Mastered
Ørsted's discovery, the magnetic field around a straight current-carrying wire and the right-hand grip rule, B = μ₀I/2πr, adding fields from two wires, the field of a single loop, the field inside a solenoid (B = μ₀NI/L), electromagnets, and the compass-deflection investigation.
-
4K Electricity and magnetism review Mastered
Module 4 review: summary of electrostatics, circuits and magnetism, every formula with its symbols and units, a comparison of gravitational, electric and magnetic fields, a multi-step worked problem, and a mixed HSC-style test.