Cambridge IGCSE Physics 0625: Command words and keywords

Cambridge IGCSE Physics (0625) uses the standard Cambridge command words. As with other sciences, mark schemes reward precise physical terminology and correct response to command words. Examiners apply science-specific marking principles: keywords must be used correctly in context.

Command words in Physics 0625

Command word	What to do in Physics	Common mistake
State	Short answer; one point per mark	Long explanation
Define	Precise meaning (often with equation)	Vague or incomplete
Describe	What happens; no “why”	Adding explanation
Explain	Why or how; use “because”	Only describing
Suggest	Apply to new context	Textbook recall
Calculate	Show working; correct formula; units	Wrong formula or units
Show that	Prove the given value with calculation	No working
Determine	Find numerical answer with working	Guess or no working
Plot	Graph from data; line of best fit	Wrong scale or no line
Draw	Circuit diagram; ray diagram; correct symbols	Wrong symbols or layout
Sketch	Rough graph/diagram; key features	Too detailed or wrong shape
Predict	What will happen based on physics	Unsupported
Compare	Similarities and differences	No comparative language
Evaluate	Judge; conclude with evidence	No conclusion

Keywords examiners look for

Physics mark schemes reward syllabus terminology. Correct use of terms and correct units are essential.

Mechanics

Term	Use correctly	Avoid
Speed	Distance / time (scalar)	Velocity (vector)
Velocity	Displacement / time; direction (vector)	Speed
Acceleration	Change in velocity / time	”Getting faster” (vague)
Force	N (newton)	Wrong unit
Weight	Force due to gravity; mg	Mass (kg)
Mass	kg; amount of matter	Weight (N)
Momentum	mass × velocity; kg m/s	Wrong unit
Work done	Force × distance; J	”Effort”
Power	Work / time or energy / time; W	”Strength”
Efficiency	(useful output / total input) × 100%	Wrong formula
Resultant force	Net force; vector sum	Single force
Equilibrium	No resultant force; no resultant moment	”Balanced” (vague)

Energy and thermal physics

Term	Use correctly	Avoid
Kinetic energy	½mv²; J	Wrong formula
Gravitational potential energy	mgh; J	Wrong formula
Specific heat capacity	Energy to raise 1 kg by 1°C	”Heat capacity”
Specific latent heat	Energy for change of state (no temp change)	“Latent heat” (needs “specific”)
Conduction	Through solids; vibrating particles	Convection
Convection	In fluids; circulating currents	Conduction
Radiation	Infrared; no medium needed	Conduction/convection
Conductor	Allows heat/electricity	Insulator
Insulator	Poor conductor	Conductor

Waves

Term	Use correctly	Avoid
Amplitude	Max displacement from equilibrium	”Height”
Frequency	Hz; waves per second	”Speed”
Wavelength	m; distance for one cycle	”Length”
Reflection	Angle of incidence = angle of reflection	Wrong law
Refraction	Change in speed; bending	”Bending” only
Critical angle	Angle for 90° refraction	Wrong angle
Total internal reflection	When angle > critical angle	Incomplete
Longitudinal	Direction of vibration
Transverse	Direction of vibration ⊥ direction of travel	Longitudinal

Electricity and magnetism

Term	Use correctly	Avoid
Current	A; flow of charge	”Flow” (vague)
Potential difference	V; work per unit charge	”Voltage” (acceptable but Pd preferred)
Resistance	V/I; Ω	Wrong formula
Ohm’s law	V = IR (for Ohmic conductor)	Wrong conditions
Series	Same current; shared pd	Parallel
Parallel	Same pd; shared current	Series
Electromotive force (e.m.f.)	Energy per unit charge from source	Potential difference
Magnetic field	Region where force acts on magnet/current	Vague
Electromagnetic induction	Induced e.m.f. when field changes	Wrong context

Nuclear physics

Term	Use correctly	Avoid
Alpha	⁴₂He; 2 protons, 2 neutrons	Beta
Beta	⁰₋₁e; electron from nucleus	Alpha
Gamma	Electromagnetic wave; no mass	Particle
Half-life	Time for half to decay	”Half the time”
Ionisation	Removal of electrons	”Radiation”
Irradiation	Exposed to radiation	Contamination
Contamination	Radioactive material on/in body	Irradiation

Mark scheme principles

• Show working—method marks available even if final answer wrong.
• Units—required; wrong or missing units can cost marks.
• Significant figures—match the data or follow instructions.
• Keywords in context—correct scientific use.
• Alternative answers—mark schemes list acceptable wording.

Common mistakes from examiner reports

• Weight vs mass—weight in N, mass in kg.
• Speed vs velocity—velocity has direction.
• Formula errors—wrong equation (e.g. KE = mv² instead of ½mv²).
• Units—missing or wrong (e.g. m instead of m/s).
• Circuit symbols—wrong or misdrawn.
• Describe vs Explain—description when explanation required.
• Rounding—too many or too few significant figures.

Tips for Physics 0625

1. Learn formulae with correct symbols and units.
2. Show working in every calculation.
3. Check units—convert before substituting.
4. Use syllabus terms—check mark scheme for acceptable wording.
5. Draw diagrams clearly with correct symbols.
6. Past papers + mark schemes show what scores.

How Tutopiya helps

Tutopiya supports Physics 0625 with tutors who use past papers, mark schemes and examiner insights. Explore IGCSE resources or book a free trial.

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Based on Cambridge IGCSE Physics 0625 syllabus and mark schemes. Check the latest syllabus for your exam series.