Unit 3: Gravity and Electromagnetism

WACE Year 12 Physics Unit 3 content point on gravitational fields and energy. Field strength as force per unit mass, field-line representation, near-surface and changing potential energy, and the work done moving a mass in a field.

Gravitation and orbital motion. Newton's law of gravitation, gravitational field strength, projectile and circular motion, and deriving orbital speed and Kepler's third law for satellites.

WACE Year 12 Physics Unit 3 content point on satellites and orbits. Gravity as the centripetal force, deriving orbital speed and period, Kepler's third law, and the special case of geostationary satellites.

Electric fields and potential. Coulomb's law, field strength for point charges and parallel plates, work, potential difference and the motion of a charge in a uniform field.

WACE Year 12 Physics Unit 3 content point on generators. How a rotating coil induces a sinusoidal emf, the role of slip rings versus a commutator, the shape of the output, and what controls the peak voltage.

WACE Year 12 Physics Unit 3 content point on Newton's law of universal gravitation. The inverse-square force law, the gravitational constant, treating bodies as point masses, and how surface gravity relates to mass and radius.

WACE Year 12 Physics Unit 3 content point on Coulomb's law. The inverse-square electrostatic force, attraction and repulsion of point charges, comparison with gravitation, and adding forces from several charges as vectors.

WACE Year 12 Physics Unit 3 content point on the motor effect. The force on a current-carrying wire, the right-hand rule for direction, the torque on a current loop, and how a DC motor produces continuous rotation.

Magnetism and moving charges. The force on a moving charge and a current-carrying conductor, the right-hand rule, circular motion in a field and the motor effect.

WACE Year 12 Physics Unit 3 content point on uniform circular motion. Centripetal acceleration and force, horizontal circles, banked tracks and vertical circles, and identifying which real force supplies the centripetal requirement.

WACE Year 12 Physics Unit 3 content point on transformers and the grid. The turns-ratio equation, ideal power conservation, why transformers need AC, and why transmitting at high voltage cuts resistive line losses.

Electromagnetic induction. Magnetic flux, Faraday's law, Lenz's law, induced emf, and the operation of AC generators and transformers.

WACE Year 12 Physics Unit 3 content point on projectile motion. Resolving velocity into components, applying constant horizontal velocity and constant vertical acceleration, and finding range, time of flight and maximum height.

WACE Year 12 Physics Unit 3 content point on charged particles in uniform fields. The field between parallel plates, the constant force on a charge, energy gained through a potential difference, and parabolic deflection like a projectile.