O Level Physics 5054 — the whole syllabus, free.

Assessment objectives: AO1 Knowledge with understanding 50%, AO2 Handling information and problem-solving 30%, AO3 Experimental skills 20%. Papers 3 and 4 are entirely AO3 — which is why the practical section of this guide matters as much as any topic.

Values worth knowing

• g ≈ 9.8 N/kg (some questions use 10 N/kg — use the value the question gives)
• Speed of all electromagnetic waves in a vacuum = 3.0 × 10⁸ m/s (air is approximately the same)
• Speed of sound in air ≈ 330–350 m/s
• Audible frequency range for humans: 20 Hz to 20 000 Hz; ultrasound is above 20 kHz
• Water at standard atmospheric pressure: melts at 0 °C, boils at 100 °C
• Light takes about 500 s to reach Earth from the Sun; Earth orbits in ≈365 days and spins in ≈24 hours

Loading…

Clear my ticks

1.1Physical quantities and measurement techniques

Measuring length: tapes and rulers for larger lengths; a micrometer for small ones (you must be able to read an analogue micrometer scale). Volume: use a measuring cylinder for liquids, and displacement for an irregular solid that sinks — the rise in liquid level equals the solid's volume. Time: clocks and digital timers.

1.2Motion

A deceleration is a negative acceleration. Uniform acceleration means the velocity changes by equal amounts in equal times (e.g. free fall near Earth); non-uniform means it does not (e.g. a car in traffic).

1.3Mass and weight

Measuring: mass with an electronic balance (or compare masses with a beam/equal-arm balance, since equal weights mean equal masses); weight with a force meter (spring balance) in newtons.

1.4Density

1.5Forces

1.5.1 Balanced and unbalanced forces. Types of force to know: weight (gravitational), friction, drag, air resistance, tension (elastic), electrostatic, magnetic, thrust (driving) and contact force. You must be able to draw free-body diagrams showing the forces on one object.

1.5.2 Friction. Friction is a force that may impede motion and produce heating. With a constant driving force, an object speeds up until drag (air resistance) grows equal to the driving force — then the resultant force is zero and it moves at constant terminal velocity.

1.5.3 Elastic deformation. Forces can change an object's size and shape.

1.5.4 Circular motion. An object moves in a circle because a force acts perpendicular to its motion. Qualitatively: with mass and radius constant, a bigger force means a bigger speed; with mass and speed constant, a bigger force means a smaller radius; a bigger mass needs a bigger force for the same speed and radius. (The equation F = mv²/r is not required.)

1.5.5 Turning effect of forces.

1.5.6 Centre of gravity. The centre of gravity is the point at which the whole weight of an object may be considered to act. Find it for a plane lamina by hanging it freely from two or three different points and drawing a plumb line each time — the lines cross at the centre of gravity. An object is more stable when its centre of gravity is low and its base is wide, because it must be tilted further before its line of action of weight falls outside the base.

1.6Momentum

1.7Energy, work and power

1.7.1 Energy stores: kinetic, gravitational potential, chemical, elastic (strain), nuclear, electrostatic and internal (thermal). Energy is transferred between stores by forces (mechanical work), electrical currents (electrical work), heating, and by electromagnetic, sound and other waves.

1.7.3 Energy resources. Know how useful energy or electrical power is obtained from: fossil fuels, biofuels, hydroelectric, solar, nuclear, geothermal, wind, tides and waves — referring to a boiler, turbine and generator where used. Compare them on whether they are renewable, when/whether they are available, and their environmental impact.

1.8Pressure

Everyday consequences: a sharp knife has a very small area so the same force gives a very large pressure; a camel's wide foot or a tractor's wide tyres spread weight over a large area, reducing pressure so it does not sink.

In a liquid, pressure increases with depth and with the density of the liquid. A liquid barometer uses the height of a liquid column that atmospheric pressure can support to measure that atmospheric pressure.

2.1Kinetic particle model of matter

Changes of state: melting (solid→liquid), solidification/freezing (liquid→solid), boiling and evaporation (liquid→gas), condensation (gas→liquid). Gas↔solid transfers are not required.

Brownian motion: smoke particles viewed under a microscope move in random, jerky paths because they are bombarded unevenly by fast-moving, invisible air molecules — direct evidence for the particle model.

2.2Thermal properties and temperature

2.2.1 Thermal expansion. Heating makes particles vibrate/move more and take up more space, so materials expand. Order of expansion for the same temperature rise: gases > liquids > solids. Applications and consequences: the liquid-in-glass thermometer (liquid expands up a narrow tube), expansion gaps in bridges and railway lines, and bimetallic strips.

2.2.2 Specific heat capacity. Raising an object's temperature increases its internal energy — specifically the average kinetic energy of all its particles.

2.2.3 Melting, boiling and evaporation. During melting, solidification, boiling and condensation, energy is transferred without a change in temperature — this is latent heat, the energy required to change the state of a substance. It goes into breaking (or forming) the forces between particles rather than speeding them up. For water at standard atmospheric pressure: melting point 0 °C, boiling point 100 °C.

Evaporation is the escape of the more energetic particles from the surface of a liquid. It is faster at higher temperature, with larger surface area, and with air movement over the surface. It causes cooling because the particles left behind have a lower average kinetic energy — and average kinetic energy is what temperature measures.

2.3Transfer of thermal energy

Surfaces and radiation: dull black surfaces are the best emitters and best absorbers; shiny white/silver surfaces are the poorest emitters and absorbers, and the best reflectors. The rate of emission increases with higher surface temperature and larger surface area.

Everyday applications: metal pans conduct heat quickly to food; a room heater warms a room by convection currents; an infrared thermometer detects emitted radiation to measure temperature without contact; a vacuum flask and building insulation reduce all three transfers (vacuum stops conduction and convection; silvered surfaces reduce radiation).

3.1General properties of waves

Wave behaviours: reflection at a plane surface (wave bounces back, speed and wavelength unchanged); refraction due to a change of speed (in a ripple tank, caused by a change in water depth); diffraction through a gap or at an edge (waves spread out). Diffraction is greatest when the gap size is similar to the wavelength; a wide gap causes little spreading, and longer wavelengths diffract more at an edge.

3.2Light

3.2.1 Reflection. The normal is the line drawn at right angles to the surface at the point where the ray strikes. The angle of incidence and angle of reflection are both measured from the normal.

3.2.2 Refraction. Light changes speed when it enters a different medium, so it changes direction (unless it enters along the normal).

Optical fibres use total internal reflection to carry light signals along a curved path. In telecommunications this gives very high data rates, low signal loss over long distances, immunity to electrical interference, and cables that are thinner and lighter than copper.

3.2.3 Thin lenses. A converging (convex) lens brings a parallel beam to a focus; a diverging (concave) lens spreads a parallel beam out. The principal axis is the line through the centre of the lens perpendicular to it; the principal focus (focal point) is where rays parallel to the principal axis converge; the focal length is the distance from the lens to the principal focus.

Magnifying glass: a single converging lens with the object placed closer than the focal length gives an enlarged, upright, virtual image.

Eye defects: a short-sighted eye focuses distant objects in front of the retina — corrected with a diverging lens. A long-sighted eye focuses near objects behind the retina — corrected with a converging lens.

3.2.4 Dispersion. A glass prism refracts white light by different amounts for different colours, splitting it into a spectrum. The seven traditional colours in order are red, orange, yellow, green, blue, indigo, violet — red has the longest wavelength and lowest frequency; violet has the shortest wavelength and highest frequency.

3.3Electromagnetic spectrum

All electromagnetic waves are transverse, travel at 3.0 × 10⁸ m/s in a vacuum (approximately the same in air), and can travel through a vacuum.

Damage: excessive exposure heats soft tissues and causes burns. Ionising effects come from ultraviolet (skin cancer, cataracts), X-rays and gamma rays (cell mutation and cancer).

3.4Sound

Sound is produced by vibrating sources and travels as a longitudinal wave made of compressions (particles pushed together, high pressure) and rarefactions (particles spread apart, low pressure).

• Sound cannot travel through a vacuum because it needs particles to transmit the vibrations. Demonstration: a ringing electric bell inside a bell jar becomes inaudible as the air is pumped out, though it can still be seen vibrating.
• Human audible range: 20 Hz to 20 000 Hz. Ultrasound is sound above 20 kHz.
• Greater amplitude → louder sound. Greater frequency → higher pitch. Different sources give different qualities (timbres), seen as different waveform shapes on an oscilloscope.
• Speed of sound in air ≈ 330–350 m/s. In general sound travels faster in solids than liquids, and faster in liquids than gases (particles are closer, so vibrations pass on more quickly).
• An echo is the reflection of sound waves.

Uses of ultrasound: cleaning delicate objects, prenatal and other medical scanning, and sonar for measuring depth or locating objects.

4.1Simple magnetism and magnetic fields

• Like poles repel, unlike poles attract. A magnet also attracts unmagnetised magnetic materials (iron, steel, cobalt, nickel) by induced magnetism — the material becomes a magnet while in the field.
• A magnetic field is a region in which a magnetic pole experiences a force. Its direction at a point is the direction of the force on a north pole placed there, so field lines run from N to S outside a magnet.
• Field strength is shown by the spacing of the field lines — closer lines mean a stronger field.
• Plotting fields: with a plotting compass (mark the needle's direction at successive points) or by sprinkling iron filings.

4.2Electrical quantities

4.2.1 Charge. Charge is positive or negative, measured in coulombs (C). Unlike charges attract, like charges repel. Charging a solid by friction involves the transfer of negative charge (electrons) only — rub a polythene rod with a cloth and electrons move onto the rod, leaving the cloth positive. An electric field is a region in which a charge experiences a force; the field direction is the direction of the force on a positive charge.

Conductors (metals, graphite) have free electrons that can move through the material; insulators (plastic, glass, rubber) have electrons bound to atoms and cannot conduct.

4.2.2 Current.

In metals, current is the movement of free electrons. Conventional current flows from positive to negative; the free electrons actually flow from negative to positive. d.c. flows in one direction only; a.c. repeatedly reverses direction. Ammeters are connected in series.

4.2.3 e.m.f. and p.d.

Voltmeters are connected in parallel across the component.

4.2.4 Resistance.

For a wire: resistance is directly proportional to length and inversely proportional to cross-sectional area — a longer, thinner wire has more resistance.

4.3Electric circuits

You must be able to draw and interpret circuit diagrams containing cells, batteries, power supplies, generators, oscilloscopes, potential dividers, switches, fixed and variable resistors, heaters, thermistors (NTC), LDRs, lamps, motors, ammeters, voltmeters, magnetising coils, transformers, fuses, relays, diodes and LEDs.

4.3.3 Input sensors and potential dividers. An NTC thermistor's resistance decreases as temperature increases. An LDR's resistance decreases as light intensity increases. Both are used as input sensors in potential divider circuits — as their resistance changes, the share of the supply voltage across them changes, which can switch a circuit on or off (fire alarms, automatic lighting).

4.4Practical electricity

Common uses of electricity: heating, lighting, battery charging, powering motors and electronic systems. Lamps are connected in parallel in a lighting circuit so that each gets the full mains voltage, each can be switched independently, and one failing does not break the others' circuit.

4.4.2 Electrical safety. Hazards: damaged insulation, overheating cables, damp conditions, and excess current from overloading plugs, extension leads and sockets.

• A fuse is a thin wire that melts and breaks the circuit if the current exceeds its rating; a trip switch (circuit breaker) does the same job automatically and can be reset. Choose a rating just above the appliance's normal operating current.
• Fuses and switches must be in the live wire, so that when they break the circuit the appliance is isolated from the high voltage. A switch in the neutral wire would stop the current but leave the appliance at live potential — still dangerous.
• The mains has a live (line), neutral and earth wire. If a live wire touches an earthed metal case, a very large current flows to earth, which blows the fuse and disconnects the supply — preventing the case from becoming live.
• An appliance's outer casing must be either earthed or non-conducting (double-insulated).

4.5Electromagnetic effects

4.5.1 Electromagnetic induction. When a conductor cuts magnetic field lines (or the field through a coil changes), an e.m.f. is induced. The induced e.m.f. is larger with a faster movement, a stronger magnetic field, or more turns on the coil.

4.5.2 The a.c. generator. A coil rotating in a magnetic field (or a rotating magnet) induces an alternating e.m.f., taken off through slip rings and brushes. The e.m.f. is maximum when the coil is parallel to the field lines (cutting them fastest) and zero when it is perpendicular to them (moving along the lines, cutting none).

4.5.3 Magnetic effect of a current. A current in a straight wire produces circular field lines around it; a solenoid produces a field like a bar magnet's, strong and uniform inside. Increasing the current strengthens the field; reversing the current reverses the field direction. Used in relays (a small current switches a larger circuit) and loudspeakers (varying current in a coil in a magnetic field moves the cone to produce sound).

4.5.4 Force on a current-carrying conductor. A wire carrying a current in a magnetic field experiences a force (the motor effect). Reversing either the current or the field reverses the force; reversing both leaves it unchanged. Force, field and current are mutually perpendicular.

4.5.5 The d.c. motor. A current-carrying coil in a magnetic field experiences a turning effect, increased by more turns, a larger current, or a stronger field. The split-ring commutator reverses the current in the coil every half turn, so the coil keeps rotating in the same direction rather than stopping in a vertical position.

4.5.6 The transformer. An alternating current in the primary coil produces a changing magnetic field in the soft-iron core, which induces an alternating e.m.f. in the secondary coil. Step-up transformers increase voltage (more turns on the secondary); step-down decrease it.

4.6Uses of an oscilloscope

An oscilloscope displays waveforms (you do not need to know its internal structure). It can measure p.d. and short time intervals.

5.1The nuclear model of the atom

5.1.1 The atom. An atom has a positively charged nucleus with negatively charged electrons in orbit around it.

5.1.2 The nucleus. The nucleus contains protons and neutrons. Atoms form positive ions by losing electrons and negative ions by gaining electrons.

5.2Radioactivity

5.2.1 Detection. Alpha particles can be detected with a cloud chamber or spark counter; beta particles and gamma radiation with a Geiger-Müller tube and counter. Count rate is measured in counts/s or counts/minute.

5.2.2 The three emissions. Emission from a nucleus is spontaneous and random in direction.

5.2.3 Decay equations.

5.2.4 Fission and fusion. Fusion is the formation of a larger nucleus by combining two smaller nuclei, releasing energy — this powers the stars. Fission is when a large nucleus such as U-235 absorbs a neutron and splits into daughter nuclei plus two or more neutrons, releasing energy. Those neutrons can cause further fissions — a chain reaction. In a reactor this is controlled by control rods (absorb neutrons to control the rate), a moderator (slows neutrons so they cause further fission) and a coolant (carries energy away to generate steam).

5.2.5 Half-life.

Carbon dating: living things absorb carbon-14; when they die, absorption stops and the C-14 decays with a known half-life, so the remaining proportion gives the age.

5.2.6 Safety. Ionising radiation causes cell death, mutations and cancer in living things. Reduce risk by: reducing exposure time, increasing distance between source and body, and using shielding (lead, thick concrete) to absorb the radiation. Handle sources with tongs, point them away from people, and store them in lead-lined containers.

6.1Earth and the Solar System

• The Earth orbits the Sun once in approximately 365 days, along an ellipse that is approximately circular.
• The Earth rotates once on its tilted axis in approximately 24 hours (this gives day and night; the tilt gives the seasons).
• The Moon takes approximately one month to orbit the Earth.
• Light from the Sun takes approximately 500 s to reach the Earth.

The Solar System contains one star (the Sun), eight planets — in order from the Sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune — plus minor planets (dwarf planets such as Pluto, and asteroids in the asteroid belt), moons orbiting planets, and smaller bodies including comets and natural satellites.

• The force keeping objects in orbit around the Sun is the Sun's gravitational attraction.
• Gravitational field strength at a planet's surface depends on the planet's mass, and decreases with distance from the planet.
• The Sun contains most of the mass of the Solar System, so its surface gravitational field strength is greater than any planet's.
• The Sun's gravitational field strength decreases with distance, and so orbital speeds of the planets decrease the further they are from the Sun (and their orbital periods increase).

6.2Stars and the Universe

6.2.1 The Sun as a star. The Sun is a medium-sized star made mostly of hydrogen and helium, radiating most of its energy in the infrared, visible and ultraviolet regions. Stars are powered by nuclear reactions; in stable stars this is the fusion of hydrogen into helium.

6.2.2 Stars and galaxies. Galaxies each contain many billions of stars. The Sun is a star in the Milky Way, whose diameter is about 100 000 light-years. Other Milky Way stars are much further from Earth than the Sun is. A light-year is the distance travelled in a vacuum by light in one year.

6.2.3 The Universe. The Milky Way is one of many billions of galaxies making up the Universe.

The experimental contexts you must be familiar with

• Measuring physical quantities such as length, volume or force
• Measuring small distances or short time intervals
• Determining a derived quantity — extension per unit load for a spring, a resistance value, an acceleration
• Testing a relationship between two variables, e.g. p.d. across a wire against its length
• Comparing measured quantities (such as angles of reflection) or derived quantities (such as density)
• Cooling and heating, including temperature measurement
• Experiments using springs and balances; timing motion or oscillations
• Electric circuits — connecting and reconnecting circuits, measuring current and p.d.
• Optics — optical pins, mirrors, prisms, lenses, glass or Perspex blocks (rectangular and semicircular)
• Unfamiliar procedures with simple apparatus (they will describe what to do — read carefully)

Planning: the language that earns marks

A good plan states: the apparatus, how to measure each quantity, a sensible range and number of values (usually at least 5–6 spread across a wide range), what to keep constant, how results will be recorded, how they will be processed (often a graph), and the safety precautions.

Taking readings

• Read to the nearest half-scale division where required (e.g. a ruler marked in mm can be read to 0.5 mm).
• Correct for zero errors — if a force meter reads 0.2 N with nothing attached, subtract 0.2 N from every reading.
• Avoid parallax error: read at eye level, perpendicular to the scale; use a mirror behind the pointer if provided.
• Repeat readings and average them, especially for timings.
• Time multiple oscillations (e.g. 20) and divide, to reduce the percentage uncertainty from reaction time.
• Record all readings to the same number of decimal places, consistent with the instrument's precision.

Graphs — where marks are most often lost

Evaluating: errors, improvements and conclusions

Safety precautions should match the hazard: hot apparatus → use tongs/heatproof mat and allow to cool; masses on a spring → keep feet clear and use a soft landing; electrical work → switch off between changes and avoid overheating the wire; light sources and lasers → never look directly at the beam.

Official (free)

• Cambridge International — 5054 subject page: syllabus, specimen papers, past papers, mark schemes and examiner reports.
• Examiner reports say exactly which definitions and explanations candidates got wrong each series — read them for every paper you attempt.

Free archives

• GCE Guide — past papers by year and variant.
• PastPapers.co — full CAIE archive including P3/P4 practical papers.
• Physics & Maths Tutor — topic-sorted questions.

A method that fits how physics is marked

1. Definitions first. Write the definitions bank on cards and test yourself until the wording is automatic — that is pure AO1, half the paper.
2. Equations second. Write out the full equation list from blank paper once a week. Nothing is given to you in the exam.
3. Then calculations. Always: write the equation, substitute with units, then evaluate. Method marks survive an arithmetic slip; a bare wrong answer scores nothing.
4. Explanations third. Practise the standard "explain in terms of particles/forces/energy" answers out loud until they are structured, not vague.
5. Do not skip the practical paper. Work through past P3/P4 papers specifically — 20% of your grade, and the questions repeat their patterns heavily.