Secondary 6 Physics

Motion along a circular path at constant speed; the speed is constant but the direction of velocity keeps changing.

The angle swept per unit time, in rad s⁻¹; equal to 2π divided by the period.

The time for one complete revolution; the reciprocal of the period is the frequency of rotation.

The acceleration of circular motion directed towards the centre, of magnitude v²/r.

The net force towards the centre that keeps an object in circular motion, mv²/r, provided by real forces such as tension, friction or gravity.

Any two objects attract each other with a force proportional to the product of their masses and inversely proportional to the square of their separation: F = Gm₁m₂/r².

The constant G in the law of gravitation, 6.67 × 10⁻¹¹ N m² kg⁻².

The gravitational force per unit mass at a point, GM/r²; about 9.8 N kg⁻¹ at the Earth's surface.

An object orbiting a planet or star; for an artificial satellite, gravity supplies the centripetal force for the orbit.

The path of an object moving around a celestial body under gravity; the speed of a circular orbit is v = √(GM/r).

A directed flow of charge, equal to the charge passing per second, I = Q/t, measured in amperes (A).

The energy converted per unit charge passing between two points, in volts (V); it drives the current.

A conductor's opposition to current, equal to voltage divided by current, in ohms (Ω).

For a metallic conductor at constant temperature, voltage is proportional to current: V = IR.

Components chained end to end: the current is common, R = R₁ + R₂ + …, and voltage divides in proportion to resistance.

Components connected across the same pair of nodes: the voltage is common, 1/R = 1/R₁ + 1/R₂, and current divides inversely with resistance.

The rate at which an appliance converts electrical energy: P = VI = I²R = V²/R, in watts (W).

The commercial unit of electrical energy: the energy used by a 1 kW appliance in one hour, 3.6 × 10⁶ J — one 'degree'.

A low-melting-point wire that melts and breaks the circuit when the current exceeds its rating; it must be fitted in the live wire.

The wire connecting an appliance's metal casing to the ground, carrying leakage current away to prevent electric shock.

The region around a magnet or current where magnetic forces act, represented by field lines running from the north pole to the south pole.

The phenomenon that a current produces a magnetic field around it, first discovered by Oersted.

The rule for finding the field direction around a current: the thumb points along the current and the curled fingers give the field direction.

A coil wound into a cylinder; when current flows, its field resembles that of a bar magnet.

A solenoid with a soft-iron core; its magnetism grows with current and turns, and disappears almost entirely when switched off.

The rule for the force on a current-carrying conductor in a field: first finger along the field, second along the current, thumb along the force.

The phenomenon, discovered by Faraday, that a changing magnetic flux through a circuit induces an e.m.f.

The e.m.f. produced in a circuit by a changing magnetic flux; an induced current flows only when the circuit is closed.

The induced current always opposes the change in flux that produces it — a consequence of energy conservation.

A device that changes a.c. voltages by electromagnetic induction, Vs/Vp = Ns/Np; it works only with alternating current.

The spontaneous emission of radiation by unstable nuclei as they change into other nuclides, unaffected by temperature, pressure or chemical state.

Radiation of helium nuclei (2 protons + 2 neutrons), positively charged; least penetrating, most ionizing.

Radiation of high-speed electrons, negatively charged; intermediate in both penetration and ionizing power.

Very short-wavelength electromagnetic waves, uncharged; most penetrating, stopped only by thick lead or concrete, and least ionizing.

The ability of radiation to ionize atoms: α strongest, β next, γ weakest — inversely related to penetrating power.

The process by which an unstable nuclide spontaneously emits radiation and changes into another nuclide; when any single atom decays is unpredictable.

The time for the number (or activity) of a radioactive nuclide to halve; each half-life multiplies the remainder by one half.

The number of decays per second in a sample, in becquerels (Bq); activity halves each half-life just like the nucleus count.

The ever-present natural and artificial radiation in the environment, mainly from cosmic rays, rocks and soil, food and medical examinations.

An instrument that detects radiation as a count rate, commonly used to measure a sample's activity and background levels.

The number of protons Z in a nucleus, fixing the element's identity and chemical properties.

The total number A of protons and neutrons in a nucleus.

The notation for a nuclide: mass number A top-left, atomic number Z bottom-left, element symbol to the right.

Nuclides with the same atomic number but different neutron numbers; chemically identical, though their nuclear properties may differ greatly.

Thomson's atomic model: positive charge spread evenly with electrons embedded like plums in a pudding.

The α-particle-on-gold-foil experiment: a few sharp deflections and rebounds proved a tiny, positively charged nucleus.

The discrete states electrons may occupy in Bohr's model; transitions absorb or emit specific energies.

The splitting of a heavy nucleus (e.g. uranium-235) by neutron impact into lighter nuclei with released neutrons and energy; the energy source of nuclear power plants.

The merging of light nuclei into heavier ones at extreme temperature and pressure; the Sun's energy source.

Einstein's equation E = mc²: the energy from a mass defect equals the lost mass times the speed of light squared.

The content every candidate must study, examined in Paper 1 at 60% of the total over 2.5 hours.

The part examined by choosing any two of the four elective units, Paper 2 at 20% in 1 hour.

Objective items with four options; numerous and time-pressured, they reward speed with accuracy.

Long questions broken into parts, marked step by step, balancing calculation and explanation.

Assessment administered by schools on practical work across S5 and S6, worth 20% of the total.

The reporting system that matches performance against defined standards, Levels 1 to 5, with 5** for the very best.

The share of the total mark carried by each paper or topic; use weightings to prioritise revision time.

The official guide listing scoring points per step; use it to audit your own answering format during revision.

Planning time per section by question count and marks: easy items first, with time reserved to check.

The recurring errors of past candidates — missing units, series/parallel mix-ups, half-life slips; organise your mistake notebook around them.