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Understanding command words is essential for answering exam questions correctly. The command word tells you exactly what the examiner expects — if you misread it, you will lose marks even if your physics knowledge is correct. This lesson covers every command word used in the Edexcel GCSE Physics (1PH0) papers, with physics-specific worked examples.
Every exam question begins with (or contains) a command word — an instruction telling you what kind of answer is required. If a question says "Describe" and you give an explanation, you may not get full marks. If it says "Calculate" and you estimate, you will score zero.
Exam Tip: Before writing anything, circle or underline the command word. This forces you to think about what type of answer is needed.
What it means: Recall a fact. Write a short answer — a word, phrase, or single sentence. No explanation is needed.
Example:
State the unit of force.
Answer: Newton (N)
Example:
Give one example of a non-renewable energy resource.
Answer: Natural gas
Example:
Name the type of wave that cannot travel through a vacuum.
Answer: Longitudinal wave / sound wave
Exam Tip: These are typically 1-mark questions. Keep your answer concise — one clear statement is enough. Do not waste time writing paragraphs.
What it means: Say what happens, step by step. You do NOT need to explain why — just state the observations or sequence of events.
Example:
Describe the motion of the skydiver shown in the velocity–time graph.
Answer: The skydiver accelerates rapidly at first. The acceleration then decreases as air resistance increases. The skydiver reaches a constant velocity (terminal velocity). When the parachute opens, the skydiver decelerates rapidly. The skydiver then reaches a new, lower terminal velocity before decelerating to rest on landing.
Example:
Describe what happens to the resistance of a filament lamp as the current increases.
Answer: As the current increases, the resistance of the filament lamp increases. This is because the filament gets hotter, causing the metal ions to vibrate more, making it harder for electrons to flow through.
Exam Tip: For "Describe" questions about graphs, work through the graph from left to right, describing each distinct section. Use data from the graph where possible.
What it means: Say what happens AND why. Use the word "because" or "this is because" to link cause and effect. This is where most marks are earned — and lost.
Example:
Explain why a car's braking distance increases when the road is wet.
Answer: When the road is wet, there is less friction between the tyres and the road surface. This means the braking force is smaller. Because the braking force is reduced, it takes longer for the car to decelerate to rest, so the braking distance increases.
Example:
Explain why the current through a resistor decreases when another resistor is added in series.
Answer: Adding a resistor in series increases the total resistance of the circuit. Because the voltage of the battery stays the same, and V = IR, an increase in resistance causes a decrease in current.
Exam Tip: For every "Explain" question, aim to write a chain of reasoning. Each sentence should logically follow from the previous one. Use physics equations to support your explanation where relevant.
What it means: Use numbers and an equation to work out an answer. You MUST show all working — even if your final answer is wrong, you can still earn method marks.
The four-step method:
Example:
Calculate the kinetic energy of a ball of mass 0.5 kg travelling at 4 m/s.
Answer:
KE = ½mv²
KE = ½ × 0.5 × 4²
KE = ½ × 0.5 × 16
KE = 4 J
Exam Tip: Always show your working, even for simple calculations. If you make an arithmetic error but your method is correct, you will still earn most of the marks. If you just write a final (wrong) answer, you get zero.
What it means: Write about both items, identifying similarities and/or differences. Use comparative words like "whereas", "however", "but", "both", "more than", "less than".
Example:
Compare the properties of transverse and longitudinal waves.
Answer: In transverse waves, the oscillations are perpendicular to the direction of energy transfer, whereas in longitudinal waves, the oscillations are parallel to the direction of energy transfer. Both types of wave transfer energy without transferring matter. Transverse waves can travel through a vacuum (e.g. electromagnetic waves), whereas longitudinal waves require a medium to travel through.
Exam Tip: A common mistake is to describe one item and then describe the other separately. You MUST make direct comparisons in the same sentence using linking words like "whereas" or "however".
What it means: Consider the advantages and disadvantages (or strengths and weaknesses), and then give a conclusion — a final judgement based on the evidence.
Example:
Evaluate the use of wind turbines as a source of electricity.
Answer:
Advantages: Wind turbines produce no greenhouse gas emissions during operation. Wind is a renewable resource that will not run out. They have low running costs once installed.
Disadvantages: Wind turbines only generate electricity when the wind is blowing, so they are unreliable. They have high initial installation costs. They can cause visual pollution and noise in rural areas. They have a relatively low power output compared to fossil fuel power stations.
Conclusion: Wind turbines are a useful part of the energy mix because they reduce carbon emissions, but they cannot be relied upon as the sole source of electricity due to their intermittent nature. They work best when combined with other energy sources or energy storage systems.
Exam Tip: "Evaluate" questions almost always require a conclusion. If you list pros and cons but do not give a final judgement, you cannot access the top marks.
What it means: Apply your physics knowledge to an unfamiliar context. There may be more than one acceptable answer. The examiner is looking for a sensible, scientifically justified response.
Example:
A student notices that a metal spoon left in a hot drink becomes warm. Suggest why.
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