O Level Physics Formula List

Key idea: Ace your O Level Physics exams with our free comprehensive formula list. Ideal for O Level students.

SEC G3 Physics 2027

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Learning objectives

Represent a physical quantity with a numerical magnitude and unit
Recall the six prescribed SI base quantities and their units
Use the prescribed SI prefixes from nano to tera
Compare orders of magnitude from a typical atom to the Earth
Select and justify measuring instruments by range and precision
Distinguish scalar and vector quantities and give examples
Add two vectors graphically to determine a resultant
State what speed means
State what velocity means, including its direction
Calculate average speed from total distance and total time
Calculate acceleration as change in velocity divided by time taken
State what uniform acceleration means
Interpret examples of non-uniform acceleration
Plot and interpret displacement–time and velocity–time graphs in one dimension
Deduce rest and uniform or non-uniform velocity from a displacement–time graph
Deduce rest, uniform velocity and uniform or non-uniform acceleration from a velocity–time graph
Use signed area under a velocity–time graph to determine displacement
Recall constant free-fall acceleration near Earth as approximately 10 m/s²
Distinguish contact forces from non-contact forces
State that mass measures the amount of matter in a body
Describe a gravitational field as a region where a mass experiences gravitational force
Define gravitational field strength as gravitational force per unit mass
Apply weight = mass × gravitational field strength
Distinguish mass from weight
Describe the effect of balanced and unbalanced forces on a body
Describe ways a force may change motion
Identify action–reaction pairs on interacting bodies
Draw free-body diagrams for force systems in at most two dimensions
Solve three-force static equilibrium graphically
Apply resultant force = mass × acceleration
Relate mass to resistance to change in motion
Explain the effects of friction on motion
Describe falling with and without air resistance, including terminal velocity
Describe a moment as a force's turning effect in everyday examples
Apply moment = force × perpendicular distance from the pivot
State the principle of moments for a body in equilibrium
apply the principle of moments to new situations or to solve related problems
show an understanding that the weight of a body may be taken as acting at a single point known as its centre of gravity
Explain qualitatively how centre-of-gravity position affects stability
Define pressure as force per unit area
Apply pressure = force ÷ area
Explain pressure transmission in a hydraulic press
Apply density = mass ÷ volume
Apply liquid-column pressure = height × density × gravitational field strength
Explain how liquid-column height measures atmospheric pressure
Explain how a manometer measures pressure difference
Recognise kinetic, potential, nuclear and internal energy stores
Describe mechanical energy transfer by a force acting over a distance
Describe electrical energy transfer by an electric current
Describe energy transfer by heating due to a temperature difference
Describe energy transfer by electromagnetic and mechanical waves
Recall and apply Ek = ½mv² in new situations
Recall and apply Ep = mgh near the Earth's surface in new situations
State and apply the principle of conservation of energy
Recall and apply work done = force × distance moved in the force direction
Recall and apply power = energy transfer / time taken
Calculate efficiency as useful energy output / total energy input
Evaluate prescribed electricity-generation resources by efficiency, cost, reliability and environmental impact
Compare physical properties of solids, liquids and gases
Explain state properties using particle arrangement, motion, forces and separation
Infer random molecular motion from a Brownian-motion experiment
Relate temperature rise to increased average kinetic energy of particles
Explain gas pressure using particle collisions with container walls
Explain heating from higher to lower temperature until thermal equilibrium
Describe conduction in solids through particle vibration and mobile electrons
Describe convection in fluids through density changes and bulk motion
Explain that energy transfer by electromagnetic radiation needs no material medium
Explain how surface colour, texture, temperature and area affect radiation transfer rate
Apply conduction, convection and radiation in everyday systems
describe internal energy as an energy store that is made up of the total kinetic energy associated with the random motion of the particles and the total potential energy between the particles in the system
Define heat capacity and specific heat capacity
Apply energy transferred = mass × specific heat capacity × temperature change
describe melting/solidification and boiling/condensation as processes of energy transfer without a change in temperature
Explain the difference between boiling and evaporation
Define latent heat and specific latent heat
Apply energy transferred for a change of state = mass × specific latent heat
Explain latent heat using particle behaviour
Sketch and interpret a cooling curve
Describe wave generation by vibrating sources, ropes and springs
Describe ripple-tank waves using wavefronts
Explain that waves transfer energy
Explain that wave energy transfer does not transfer matter
Use amplitude, frequency and wavelength to describe wave motion
Define and use wave speed and period and interpret wave graphs
Recall and apply wave speed = frequency × wavelength
Compare transverse and longitudinal waves and give examples
Explain sound production by vibration and the need for a medium
Describe sound using compressions and rarefactions
Relate sound loudness to amplitude and pitch to frequency
Explain reflected-sound echoes and use them to measure distance
Explain ultrasound use in sonar and soft-tissue scanning
State that all electromagnetic waves are transverse
State that all electromagnetic waves travel at the same speed in vacuum
Order the seven electromagnetic-spectrum regions
Relate spectrum order to wavelength and frequency
State typical uses of radio waves
State typical uses of microwaves
State typical uses of infrared
State typical uses of visible light
State typical uses of ultraviolet
State typical uses of X-rays
State typical uses of gamma rays
Describe hazardous heating effects of electromagnetic over-exposure
Describe hazardous ionising effects on living cells and tissue
Use the normal, angle of incidence and angle of reflection
Apply the law of reflection in constructions, measurements and calculations
Use the normal, angle of incidence and angle of refraction
Apply sin i divided by sin r as a constant for a fixed pair of media
Define refractive index as vacuum light speed divided by medium light speed
Explain the critical angle
Explain the conditions for total internal reflection
Apply total internal reflection to optical fibres and state advantages
Describe how a thin converging lens acts on a light beam
Define the focal length of a converging lens
Construct real and virtual image ray diagrams for a thin converging lens
Describe lens images as real or virtual, magnified or diminished, and upright or inverted
state that there are positive and negative charges and that charge is measured in coulombs
state that unlike charges attract and like charges repel
Describe an electric field as a region where charge experiences force
Recall that the field lines of an isolated point charge give the direction of the force on a positive test charge
Draw the directed electric field of an isolated point charge
Interpret the electric-field pattern between two isolated point charges
Draw the electric-field pattern between two isolated point charges
Explain charging by rubbing as electron transfer
Describe experiments that charge a conductor by induction
Describe potential electrostatic-charging hazards
Describe an electrostatic precipitator and transfer the principle
State current as rate of charge flow measured in amperes
Distinguish conventional current from electron flow
Apply charge equals current multiplied by time
Define source e.m.f. as work done per unit charge around a circuit
Calculate total e.m.f. for sources in series
Define component potential difference as work done per unit charge
State resistance as potential difference divided by current
Apply resistance equals potential difference divided by current
Apply wire-resistance proportionalities for length and cross-sectional area
Describe the effect of temperature on metallic resistance
Sketch and interpret required current–voltage characteristics
Recognise and interpret circuit symbols for cells, batteries, switches, lamps, LEDs, resistors, fuses, ammeters and voltmeters
Draw circuit diagrams with cells, batteries, switches, lamps, LEDs, fixed and variable resistors, fuses, ammeters and voltmeters
Recognise and interpret circuit symbols for d.c. and a.c. supplies, potentiometers, bells, light-dependent resistors and thermistors
Draw circuit diagrams with d.c. and a.c. supplies, potentiometers, bells, light-dependent resistors and thermistors
Apply the same-current rule in series circuits
Apply the potential-difference sum in series circuits
Apply current conservation at parallel junctions
Apply equal potential difference across parallel branches
Calculate effective resistance in series
Calculate effective resistance in parallel
Solve whole-circuit problems using consistent quantities
Describe variable-potential-divider action
Describe NTC thermistor action as an input transducer
Describe light-dependent resistor (LDR) action as an input transducer
Solve simple NTC and LDR potential-divider problems
Explain electrical heating in common appliances
Apply P = VI
Apply E = VIt
Calculate electrical energy and cost in kWh
Identify the hazard from damaged insulation
Identify the hazard from overheating cables
Identify the hazard from damp conditions
Explain how fuses and circuit breakers protect circuits
Choose and justify an appropriate fuse rating
Explain why metal casings are earthed
Explain why double-insulated appliances do not need an earth wire
State the meanings and roles of live, neutral and earth
Describe the wiring of a mains plug
Explain live-wire placement of switches, fuses and circuit breakers
State the properties of magnets
Describe induced magnetism
Distinguish temporary and permanent magnets
Determine magnetic-field direction with a compass or bar magnet
Interpret bar-magnet field patterns
Draw the magnetic field pattern around a bar magnet and between the poles of two bar magnets
Interpret the field pattern around a straight current-carrying wire
Draw the magnetic field pattern around a straight current-carrying wire
Interpret the field pattern around a current-carrying solenoid
Draw the magnetic field pattern around a current-carrying solenoid
Relate current magnitude and direction to magnetic field
Describe electromagnet applications
Describe experiments showing the force on a current-carrying conductor in a magnetic field
Describe magnetic force on a charged-particle beam
Predict force reversal when current or field reverses
Use Fleming’s left-hand rule
Explain the turning effect on a current-carrying coil
Explain how current and turns increase the turning effect
Describe split-ring commutator action
Describe the effect of winding a motor coil on a soft-iron cylinder
Deduce that a changing magnetic field can induce an e.m.f.
Deduce that induced e.m.f. opposes the change producing it
Deduce factors affecting induced e.m.f. magnitude
Describe a simple a.c. generator and slip rings
Sketch a simple a.c. generator voltage–time graph
Describe a simple iron-cored transformer
Apply ideal-transformer equations
Explain cable loss and high-voltage transmission
Describe atomic composition
Use proton number, nucleon number and isotope
Use and interpret nuclide notation
Explain random and spontaneous nuclear decay
Describe alpha, beta-minus and gamma radiation
Compare ionising effect and penetrating power
Use nuclide equations for radioactive decay
Explain background radiation
Use half-life in tables and decay curves
State radioactivity applications and hazards
Evaluate uses and hazards using half-life and radiation properties
Relate fission and fusion to nuclear-energy release
Measurements of length, mass, temperature, time interval, volume of liquids/solids and force (e.g. weight) using appropriate instruments
Determination of the density of a liquid, or of a regularly or irregularly shaped solid that sinks in water
Determination of the value of the acceleration of free fall
Investigation of the effects of balanced and unbalanced forces
The principle of moments
Determination of the position of the centre of gravity of a plane lamina
Investigation of the factors affecting transfer of energy by thermal processes
Determination of heat capacities of materials
Latent heat of substances
The law of reflection
Determination of the position and characteristics of an optical image formed by a plane mirror or a thin converging lens
The refraction of light through glass blocks
The principle of total internal reflection
The focal length of lenses
Determination of the speed, wavelength and frequency of waves
Determination of the resistance of a circuit component
Investigation of the magnetic effect of current in a conductor
Investigation of the effects of electromagnetic induction

Support page note: this is a quick-check sheet. For full learning flow, use O Level Physics Notes, O Level Quiz Hub, and Structured Practice Hub.

This is a quick-check formula and skills sheet for Singapore–Cambridge GCE O-Level Physics (6091). Optional extension material is labelled. If you don’t recognise an item, jump to the lesson page and revise. For definitions, see All Definitions Needed For O Level.

Section I: Measurement

1. Physical Quantities, Units and Measurement (notes)

Base quantities (6091):

Physical quantity	Base SI unit
Mass (m)	kilogram (kg)
Length (l)	metre (m)
Time (t)	second (s)
Current (I)	ampere (A)
Temperature (T)	kelvin (K)
Amount of substance (n)	mole (mol)

Prefixes (6091):

Number	Prefix	Symbol	Number	Prefix	Symbol
10⁻⁹	nano	n	10⁻¹	deci	d
10⁻⁶	micro	μ	10³	kilo	k
10⁻³	milli	m	10⁶	mega	M
10⁻²	centi	c	10⁹	giga	G
			10¹²	tera	T

Scalars vs vectors (must know):

Scalar: magnitude only (e.g. distance, speed, mass, time).
Vector: magnitude + direction (e.g. displacement, velocity, acceleration, force, weight).
Vector addition (graphical): place head-to-tail; resultant is start-to-end.

Instruments + zero error:

Vernier caliper: observed reading = main-scale reading immediately left of vernier zero + aligned vernier division × least count.
Micrometer: observed reading = sleeve reading (including a visible half-mm mark) + thimble division × least count.
For either instrument: correct reading = observed reading - zero error
Positive and negative zero errors are signed quantities; keep the sign when substituting.

Use the maintained vernier-caliper lesson and micrometer lesson for labelled scales and interactive practice.

Orders of magnitude (typical): atom ∼ 10⁻¹⁰ m, cell ∼ 10⁻⁵ m, human ∼ 10⁰ m, Earth ∼ 10⁷ m.

Section II: Newtonian Mechanics

2. Kinematics (notes)

Average speed: speed = (Δ d)/(Δ t)

Average velocity: v = (Δ x)/(Δ t)

Acceleration: a = (Δ v)/(Δ t)

Optional extension—equations of motion for uniform acceleration:

v = u + at
s = ut + (1/2)at²
v² = u² + 2as
s = (1/2)(u + v)t

Graphs (must know):

Displacement–time: gradient = velocity
Velocity–time: gradient = acceleration; area under graph = displacement (for uniform velocity/acceleration)

Free-fall: g ≈ 10 m s⁻² (near Earth). Always read a graph’s axes before classifying its shape; use the maintained kinematics notes for worked graph cases.

3. Dynamics (notes)

Types of forces: contact (friction, air resistance, tension, normal force) vs non-contact (gravitational, electrostatic, magnetic).

Gravitational field strength definition: g = F/m

Weight: W = mg

Newton’s laws (apply, not just state): balanced vs unbalanced forces, action–reaction pairs.

Resultant force: Fᵣₑₛᵤₗₜₐₙₜ = ma

Free-body diagrams: draw all forces acting on the object (usually at most 2D in O-Level questions).

Terminal velocity (qualitative): when weight = air resistance, resultant force = 0, acceleration = 0 (constant velocity).

4. Turning Effects of Forces (notes)

Moment (torque): M = Fd (where d is perpendicular distance from pivot)

Principle of moments (equilibrium): sum of clockwise moments = sum of anticlockwise moments

Centre of gravity (C.G.) and stability (qualitative):

Lower C.G. and wider base = more stable
Stability decreases if line of action of weight falls outside base

5. Pressure (notes)

Pressure: P = F/A

Density: ρ = m/V

Liquid column pressure: P_(due to liquid) = hρ g

Hydraulic press: F₁/A₁ = F₂/A₂

Atmospheric pressure measurement (must know):

Barometer idea: use height of liquid column to infer atmospheric pressure
Manometer: pressure difference is proportional to height difference of liquid columns

6. Energy (notes)

Work done: W = Fd (distance moved in direction of force)

Power: P = W/t = Fv (for steady speed and force along motion)

Kinetic energy: Eₖ = (1/2)mv²

Gravitational potential energy (near Earth): Eₚ = mgh

Conservation of energy: total energy before = total energy after (in a closed system)

Efficiency: efficiency = (useful energy output)/(total energy input)

Energy resources (discussion points): efficiency, cost, reliability, environmental impact (fossil vs nuclear vs solar/wind/hydro/tides/geothermal/biofuel).

Section III: Thermal Physics

7. Kinetic Particle Model of Matter (notes)

Solids/liquids/gases: compare properties using arrangement/motion/forces between particles
Brownian motion: evidence of random molecular motion
Gas pressure (idea): due to particles colliding with container walls

8. Thermal Processes (notes)

Thermal equilibrium: heat transfer stops when temperatures become equal.

Conduction (microscopic): vibrations + (in metals) movement of electrons.

Convection: density changes in fluids cause movement (warm, less dense fluid rises).

Radiation: energy transfer by electromagnetic waves; no medium required.

Good absorber/emitter of radiation: dull, black surfaces (vs shiny, white).

9. Thermal Properties of Matter (notes)

Internal energy (idea): total kinetic energy of random particle motion + total potential energy between particles.

Specific heat capacity:

E = mcΔ T

Melting/boiling/condensation/solidification: energy transfer can occur with no temperature change (during change of state).

Boiling vs evaporation (must distinguish): boiling throughout liquid at fixed boiling point; evaporation at surface at any temperature.

Specific latent heat:

E = mL

Cooling curve: recognise plateaus during change of state.

Section IV: Waves

10. General Properties of Waves (notes)

Wave speed: v = fλ

Frequency and period: f = 1/T

Sound:

Longitudinal: compressions + rarefactions
Loudness ∝ amplitude, pitch ∝ frequency
Echo distance idea: distance = vt/2
Ultrasound uses: sonar, medical scanning (soft tissue)

11. Electromagnetic Spectrum

All electromagnetic waves are transverse and travel at the same speed in vacuum.

Common uses (must know examples): radio/TV + RFID, microwaves (phones/oven/satellite), infrared (remote/thermal imaging), visible (photography/optical fibres), UV (authentication/disinfection), X-rays (imaging/security), gamma (sterilising/treating cancer).

Hazards: over-exposure causes heating effects; higher-frequency waves can be ionising (damaging cells/tissues).

Order from longest wavelength / lowest frequency to shortest wavelength / highest frequency: radio → microwave → infrared → visible → ultraviolet → X-ray → gamma. Frequency increases as wavelength decreases because c = fλ in vacuum.

12. Light (notes)

Reflection: θᵢ = θᵣ

Refraction (Snell’s law): n₁ sin θ₁ = n₂ sin θ₂

Refractive index: n = c/v

Less dense → denser: bends towards the normal
Denser → less dense: bends away from the normal

Dispersion idea: n(λ_red) < n(λ_green) < n(λ_blue)

Critical angle (for total internal reflection): sin θ_c = n₂/n₁ where n₂ < n₁

Optical fibres: apply total internal reflection + state advantages (telecom/medicine).

Thin converging lens (must know skills): focal length definition, ray diagrams, and image characteristics (real/virtual, upright/inverted, magnified/diminished). Review the maintained converging-lens ray construction table and method rather than memorising a compressed diagram.

Section V: Electricity And Magnetism

13. Static Electricity

Charge is measured in coulombs (C). Like charges repel; unlike charges attract.

Electric field (definition): region in which a charge experiences a force.

Electric field lines (must know):

Point charge: lines radiate out from + and into -
Two charges: patterns show attraction/repulsion; field line direction gives force on a positive test charge

Charging by rubbing: transfer of electrons.

Charging by induction (must know): charging without contact, using a nearby charged object.

Hazards + applications: sparks in fuel vapour; electrostatic precipitator (removing smoke particles).

14. Current of Electricity (notes)

Current: I = Q/t

Conventional current vs electron flow: opposite directions.

E.m.f.: ε = W/Q (source)

Potential difference: V = W/Q (across a component)

Resistance: R = V/I

I–V graphs (must interpret):

Ohmic conductor (constant temperature): straight line through origin
Filament lamp: curve (resistance increases as it heats)
Diode: conducts mainly one direction (threshold behaviour)

Note on gradients:

If you plot V (y-axis) against I (x-axis), gradient = R
If you plot I (y-axis) against V (x-axis), gradient = 1/R

15. D.C. Circuits (notes)

Series:

Current same everywhere
Vₜₒₜₐₗ = V₁ + V₂ + …
Rₜₒₜₐₗ = R₁ + R₂ + …

Parallel:

Potential difference same across branches
Iₜₒₜₐₗ = I₁ + I₂ + …
1/Rₜₒₜₐₗ = 1/R₁ + 1/R₂ + …

Potential divider (potentiometer idea): shares supply p.d. between components.

For two resistors in series (useful for LDR/NTC questions):

V_(out across R₂) = Vₛ R₂/(R₁ + R₂)

Input transducers in dividers:

NTC thermistor: resistance decreases when temperature increases
LDR: resistance decreases when light intensity increases

16. Practical Electricity

Power: P = VI = I²R = V²/R

Energy transferred electrically: E = VIt = Pt

Energy unit: 1 kW h = 3.6 × 10⁶ J (use for cost calculations)

Mains safety (must know):

Hazards: damaged insulation, overheating cables, damp conditions
Protection: fuses and circuit breakers (choose correct fuse rating)
Earthing vs double insulation
Live/neutral/earth roles; plug wiring; switches/fuses fitted to live wire

17. Magnetism

Magnet properties: like poles repel; unlike poles attract; magnets have N and S poles.

Induced magnetism: magnetic materials become magnetised near a strong magnet/solenoid.

Temporary vs permanent magnets: temporary (e.g. iron), permanent (e.g. steel).

Magnetic field patterns: use compass to determine direction; draw field lines around bar magnets and between poles.

18. Electromagnetism (notes)

Magnetic field due to a current: patterns around straight wire and solenoid; stronger current = stronger field.

Electromagnets: applications include circuit breakers.

Force on a current-carrying conductor / charged beam in magnetic field: use Fleming’s left-hand rule to relate force, field, current (given two, find the third).

Motor (must know): turning effect on a current-carrying coil; increased by more turns/current; split-ring commutator action.

Fleming’s left-hand rule: first finger = magnetic field (N to S), second finger = conventional current, thumb = force/motion.
Right-hand grip rule for a straight wire: thumb = conventional current, curled fingers = circular magnetic-field direction.

19. Electromagnetic Induction (notes)

Key ideas (must know):

A changing magnetic field can induce an e.m.f. in a circuit (Faraday)
Direction of induced e.m.f. opposes the change producing it (Lenz)

Ways to increase induced e.m.f.:

Use a stronger magnet
Move magnet/coil faster
Increase number of turns in coil

A.C. generator: rotating coil (or magnet), slip rings; voltage output is sinusoidal (sketch vs time).

Transformer (ideal):

Vₚ/Vₛ = Nₚ/Nₛ VₚIₚ = VₛIₛ

High voltage transmission: reduces current for same power, so reduces energy loss in cables.

Fleming’s right-hand rule for induction: first finger = magnetic field, thumb = conductor motion, second finger = induced conventional current. Keep left-hand motor force and right-hand generator induction distinct.

Section VI: Radioactivity

20. Radioactivity (notes)

Atom: nucleus (protons + neutrons) with electrons around it.

Definitions: proton number Z, nucleon (mass) number A, isotope, nuclide notation ^A_ZX.

Radioactive decay (idea): random and spontaneous; emits α, β, γ radiation.

Compare α, β, γ (must know): ionising effect and penetrating power; shielding examples.

Background radiation: always present.

Half-life:

N_final/Nᵢₙᵢₜᵢₐₗ = (1/2)ⁿ

Uses + hazards: choose sources based on half-life + penetration/ionisation.

Fusion vs fission: state meanings; both release energy.

Gas laws like Boyle’s law (P₁V₁ = P₂V₂) are commonly taught in some courses, but they are not listed in the 6091 (2026) subject content. Check your school/teacher before spending revision time here.

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Course and syllabus information

Course: SEC G3 Physics
Edition: SEC G3 Physics 2027