Hardest IGCSE Physics Questions & How to Answer Them

Stuck on tough Physics questions? You're not alone.

Those tricky 5-mark and 6-mark questions can feel impossible. You understand the simple stuff, but when the exam throws you a curveball, your mind goes blank.

Here's the thing: hard questions aren't trying to trick you. They're testing whether you really understand physics—not just whether you've memorised formulas. Can you apply what you know in new situations? Can you link different topics together? Can you explain your thinking clearly?

Good news: you absolutely can master these questions. This guide walks you through real exam questions from Cambridge and Edexcel papers. You'll see exactly how to break them down, step by step.

Save My Exams has helped thousands of IGCSE students smash their target grades. Our resources cover Cambridge, Edexcel, and OxfordAQA specifications.

Key Takeaways

• Hard questions test whether you can apply physics in new situations—not just memorise facts

• Command words like "explain" and "evaluate" tell you exactly what the examiner wants

• Always show your working step-by-step to grab method marks, even if your answer's wrong

• Tough questions appear in both Core and Extended Cambridge papers—don't underestimate either

What Makes a Physics Question Hard at IGCSE?

Not all IGCSE Physics questions are created equal. Some test basic recall. Others push you to think harder.

The trickiest questions share common features.

First, they require multi-step reasoning. You can't just plug numbers into a formula. You need to figure out which formula to use first. Then work through several calculation steps.

Second, they present unfamiliar contexts. You might know Newton's laws perfectly. But applying them to a weird scenario you've never seen? That's trickier. This tests whether you truly understand the physics.

Third, they use demanding command words. Questions asking you to "explain" or "evaluate" want much more than a simple answer. You need structured reasoning. You need specific physics terms.

Finally, they combine concepts from different topics. You might need to use knowledge about forces AND energy in the same question. This tests whether you can see the bigger picture.

Question Types to Expect in IGCSE Physics Papers

Cambridge, Edexcel, and OxfordAQA all include challenging questions in their papers. Understanding the formats helps you prepare effectively.

Multiple-Choice Questions

Don't underestimate these. Some multiple-choice questions (MCQs) are deceptively tricky.

The hardest MCQs test conceptual understanding, not just recall. You need to really understand the physics behind each option. Wrong answers are designed to catch common misconceptions.

Read each option carefully. Eliminate obviously wrong answers first. Then think through the physics for the remaining choices. Sometimes drawing a quick diagram helps you visualise what's happening.

Multi-step Calculation Questions

These questions need several steps of working. You'll identify the right equation, substitute values, maybe rearrange, then calculate.

The secret? Show every single step clearly.

Even if your final answer is wrong, you can still grab method marks for correct working. Always write the equation first. Then show your substitution. Then calculate.

And don't forget units in your final answer. So many marks lost here!

Explain and Evaluate Questions

These extended answers need structure. You're not just stating facts—you're building an argument.

First, work out what the question is really asking. Plan your answer before you write. You need clear points that link together logically. And you must use precise scientific language.

For "explain" questions, give reasons why something happens. Not just what happens—why it happens.

For "evaluate" questions, weigh up different factors. Then reach a conclusion.

Top tip: number your points. This helps you stay organised and makes sure you don't miss anything.

Practical-Based Application Questions

These test your understanding of experiments. You might need to interpret a graph, describe improvements to an experiment, or identify variables.

The examiners want specific details. Don't make assumptions about what they already know.

For fair testing, state exactly what you'd keep constant and how. For accuracy, explain how you'd measure precisely. For reliability, describe how you'd spot anomalies and calculate means.

Planning questions are especially tricky. You must describe every step of your method in detail. Act like you're writing instructions for someone who's never done the experiment before.

Hardest IGCSE Physics Questions with Model Answers

Let's tackle five genuine exam questions that students found particularly challenging. Each one comes from recent papers with examiner commentary.

Question 1: Multiple-Choice

Question (Electromagnetic Induction)

The diagram shows an electromagnet near a coil of wire connected to a voltmeter. The reading on the voltmeter is zero.

The switch is closed. The electromagnet magnetises quickly.

What happens to the reading on the voltmeter?

A. It keeps increasing.

B. It quickly increases and stays at maximum.

C. It quickly increases and then decreases.

D. It stays on zero.

Cambridge IGCSE Physics, Paper 0625/22, March 2021, Question 36 (opens in a new tab)

Model Answer

The correct answer is C

Explanation:

• When the switch closes, the electromagnet's magnetic field builds up rapidly. This changing magnetic field cuts through the coil, inducing an e.m.f. (voltage) in the coil. The voltmeter reading increases quickly.

• However, once the electromagnet is fully magnetised, the magnetic field stops changing. It's now constant. Without a changing field, no e.m.f. is induced. The voltmeter reading drops back down.

• The keyword here is "changing". You only get induced voltage when the magnetic field is actually changing—not when it's just present.

Why This Was Hard: Electromagnetic induction is one of the toughest IGCSE topics. Many students think that just having a magnetic field near a coil creates voltage. Wrong! The field must be changing.

Stronger candidates understood this. They knew the voltage would spike as the field built up, then fall back to zero once the field became steady. Weaker candidates often chose option B, thinking the voltage would stay high as long as the electromagnet was on.

Question 2: Discuss (3 Marks)

Question (Radioactivity—Contamination vs Irradiation)

A material called granite is used as a work surface in a kitchen.

Granite contains the isotope thorium-232. Thorium-232 decays to form radon-220.

Thorium-232 is a solid and remains in the work surface. Radon-220 is a gas and is emitted from the work surface.

Thorium-232 and radon-220 both emit alpha radiation.

Discuss the hazards due to the granite work surface when a person is working in the kitchen. Refer to contamination and irradiation in your answer.

Edexcel IGCSE Physics, Paper 4PH1 1P, June 2022, Question 5(c)

Model Answer

You need to explain three things clearly.

Point 1: The general hazard

• Alpha radiation is highly ionising. This means it can cause cell mutation or cancer. ✓ 1 mark

Point 2: The thorium hazard (irradiation)

• Thorium-232 is solid. It stays in the work surface. This means it can only cause irradiation—that's exposure to radiation from an external source. ✓ 1 mark

• The alpha particles can't travel far through air. So the hazard from thorium is relatively low, even if you touch the surface directly.

Point 3: The radon hazard (contamination)

• Radon-220 is a gas. This is the dangerous one. It can be inhaled or ingested (contamination). ✓ 1 mark

• This is much worse because now the alpha source is inside your body. The highly ionising alpha radiation can directly damage internal organs.

Why This Was Hard: Students often mix up contamination and irradiation. They use the terms interchangeably, which loses marks.

The question needed you to apply the definitions specifically. The solid source only causes irradiation. The gaseous source causes contamination, which is way more dangerous for alpha radiation because it gets inside your body.

Question 3: Multi-step calculation (4 Marks)

Question (Vectors—Resultant Velocity)

Fig. 1.1 shows a straight section of a river where the water is flowing from right to left at a speed of 0.54 m/s.

Fig. 1.1 (not to scale)

A swimmer starts at point P and swims at a constant speed of 0.72 m/s relative to the water and at right angles to the current.

Determine, relative to the river bank, both the magnitude and direction of the swimmer’s velocity.

Cambridge IGCSE Physics, Paper 0625/41, June 2023, Question 1(a)(i)

Model Answer

The swimmer has two velocity vectors acting at right angles:

• Swimmer's speed: (perpendicular to bank)

• Current's speed: (parallel to bank)

Step 1: Calculate the magnitude using Pythagoras' theorem

• The resultant velocity of the swimmer is:

✓ 2 marks for correct magnitude calculation

Step 2: Calculate the direction using trigonometry

• The angle to the river bank is:

to the river bank

✓ 2 marks for correct angle calculation

Alternative Method: Scale Diagram

You could also solve this graphically:

1. Choose a scale (e.g., 1 cm : 0.1 m/s)

2. Draw the current vector horizontally (5.4 cm)

3. Draw the swimmer's vector perpendicularly from the end of the current vector (7.2 cm)

4. Draw the resultant from start to finish to form a vector triangle ✓ 1 mark

5. Measure the resultant length and convert (~9.0 cm = 0.90 m/s) ✓ 1 mark

6. Identify the angle with the horizontal ✓ 1 mark

7. Measure the angle (~53°) ✓ 1 mark

Why This Was Hard: Vectors confuse many students. This question required understanding that velocities combine at right angles, not by simple addition.

Common mistakes included:

• just adding 0.72 + 0.54 instead of using Pythagoras

• drawing the diagram incorrectly

• calculating the wrong angle (not measuring from the river bank)

• forgetting to show working for both magnitude AND direction

The mark scheme shows you could use either calculation or a scale diagram—but you must show your method clearly to get full marks.

Question 4: Data Analysis (4 Marks)

Question (Astrophysics—Using Graph Data to Verify a Formula)

The graph shows the relationship between the peak wavelength of light emitted by a star and the surface temperature of the star.

A scientist suggests the two variables are linked by this formula:

Use data from the graph to justify this formula.

Edexcel IGCSE Physics, Paper 4PH1 1PR, June 2022, Question 5(c)

Model Answer

This question wants you to prove the formula works using actual numbers from the graph. Here's how.

Step 1: Read off a pair of values from the graph

• From the graph, when temperature = 5 thousand K, wavelength ≈ 580 nm

• Calculate the constant:

✓ 1 mark for reading values correctly

✓ 1 mark for calculating first constant

Step 2: Read off a different pair of values

• From the graph, when temperature = 10 thousand K, wavelength ≈ 290 nm

• Calculate the constant:

✓ 1 mark for using different pair and calculating second constant

Step 3: Compare and conclude

• Both calculations give the same constant (2900).

• Since the constant stays the same for different data pairs, the formula is supported by the graph data. ✓ 1 mark

Why This Was Hard: This question caught out loads of students. Here's why.

Many just looked at the graph and said "as temperature goes up, wavelength goes down". That's true, but it's not enough for marks. The question specifically said "use data from the graph"—meaning you need actual numbers.

Others read values but forgot to multiply them together. They just wrote the numbers down without calculating the constant.

Full marks needed three things: read two different pairs of values, multiply each pair, then state that the constants match (proving the formula works).

The trick is realising this tests Wien's displacement law—an inverse relationship where one quantity goes up as the other goes down by the same proportion.

Question 5: Practical Based Levelled Response (6 Marks)

Question (Planning an Investigation)

A steel ball is fired from a launcher on an adjustable table.

A student investigates how the range of the steel ball varies with the height of the table.

Describe a method for the student’s investigation.

Your answer should include details of

• the variables in the investigation

• how the investigation will be valid (a fair test)

• how the range will be measured accurately

Edexcel IGCSE Physics, Paper 4PH1 1P, June 2022, Question 11(a)

Model Answer

This question is worth 6 marks, so you need lots of detail. Break your answer into three sections.

Variables (2 marks):

• Independent variable: Height of the table. Measure this in cm or m using a metre rule. ✓ 1 mark

• Dependent variable: Range—the horizontal distance the ball travels along the floor. Measure this in cm or m. ✓ 1 mark

Fair Test—Control Variables (2 marks):

• Keep the launch speed constant by using the same launcher mechanism in exactly the same position for every trial. ✓ 1 mark

• Use the same type and mass of ball throughout all your measurements. ✓ 1 mark

Accurate Measurement Method (2 marks):

• Put paint on the ball to mark exactly where it lands. Use a metre rule or tape measure from directly below the launch point to the landing mark. ✓ 1 mark

• Repeat the experiment at least five times for each height. Calculate a mean value to improve reliability. ✓ 1 mark

• Make sure to identify and exclude any anomalous results before calculating the mean.

Why This Was Hard: This question sorted strong students from weaker ones. Full marks needed specific detail in all three areas.

Many students struggled with the accuracy part. Just saying "use a ruler" wasn't enough. You needed to explain how you'd identify the exact landing spot.

Others identified variables correctly but didn't explain how they'd actually keep them constant. Saying "use the same launcher" was too vague—you needed to mention keeping the launch force constant.

Strategies for Answering Tough IGCSE Physics Questions

The right strategies make all the difference. Here's how to tackle even the hardest questions with confidence.

Understand the Command Words

Command words are your secret weapon. They tell you exactly what the examiner wants.

• State or Give = Write down a fact. No explanation needed.

• Calculate = Show your working and reach an answer with units.

• Explain = Give reasons. Say why something happens, not just what happens.

• Describe = Write what happens in detail or in order. You don't need to explain why.

• Evaluate or Assess = Weigh up different factors. Make a judgment.

• Justify = Give evidence or reasoning to back up your answer.

Learn these. Definitions of all the command words used in your exam can be found in your specification.

Plan Before You Write

Never rush straight into writing. Take 30 seconds to plan.

For calculations, jot down what you know and what you need to find. Pick the right equation before you start plugging in numbers.

For extended answers, quickly note down three or four key points. This keeps your answer structured and complete. You won't accidentally miss important details.

Show All Working Clearly

Never do calculations in your head. Write every step on the paper.

Here's why: examiners give method marks for correct working, even if your final answer is wrong. But they can't give you these marks if you don't show your method.

The formula? Write the equation first. Substitute your numbers. Then calculate. This makes your logic crystal clear.

Use Specific Physics Terminology

Vague language loses you marks. Be precise.

Don't say "the thing gets bigger". Say "the resistance increases" or "the current increases".

Don't write "heat moves". Write "thermal energy is transferred by conduction".

The more specific your language, the more marks you'll score in extended answers. Physics has its own vocabulary—use it!

Common Mistakes to Avoid

Everyone makes mistakes. The trick is learning from them. Here are the most common slip-ups—and how to avoid them.

Forgetting units. This is the number one error. Always include the unit with your final answer. Check it twice.

Not reading carefully. Rushing leads to mistakes. Underline key command words. Circle important numbers. Make sure you're answering what they're actually asking.

Skipping the square root. In kinematic equations, if the equations contains , remember you need to use to calculate speed. So many students forget this step!

Picking the wrong formula. Check your equation matches the variables in the question. Don't just grab the first formula you see.

Being vague in explanations. Don't assume the examiner knows what you're thinking. Spell out each logical step clearly.

Rounding too early. Keep full values throughout your working. Only round your final answer. Early rounding creates errors that snowball.

Learn from these. Once you know what to watch for, you can avoid these mistakes completely.

Want More Practice?

Ready to tackle more tough questions? Save My Exams has everything you need to ace IGCSE Physics, including:

• IGCSE Physics Revision Notes with worked examples of exam questions carefully aligned with your exam board.

• IGCSE Physics Exam Questions Organised by topic and written by expert teachers and examiners to match your syllabus.

• Smart Mark gives you instant feedback on your answers to Exam Questions, helping you master your material more quickly.

• Target Test spots your weak areas and tells you exactly what to study next.

• IGCSE Physics Past Papers to help you practice your exam technique.

The more you practise, the easier these tough questions become. Promise.

Frequently Asked Questions

What are the hardest topics in IGCSE Physics?

Most students struggle with

• Forces and motion

• Electric circuits

• Electromagnetic induction

• Radioactivity

These need strong maths skills and clear understanding of concepts.

Practical planning questions also cause headaches. They demand really precise, detailed descriptions.

But here's the thing: "hardest" is different for everyone. Focus on your weak spots.

How do I revise for long-answer Physics questions?

Practice is everything. Work through past papers. Mark your answers against the mark scheme. Be honest with yourself.

Learn the command words inside out. Write model answers for common question types. Then test yourself without looking.

Structure your reasoning logically. Use precise scientific vocabulary. The more you practise, the more natural it becomes.

In Cambridge IGCSE Physics, are hard questions only in Extended papers?

Nope. Both Core and Extended CIE IGCSE Physics papers have challenging questions.

Core papers test the same concepts but might need slightly less detail. The hardest Core questions can be just as tough as mid-level Extended questions.

Don't underestimate either paper.

How many marks are the hardest IGCSE questions worth?

The toughest questions usually grab 4-6 marks. These are extended answers or multi-step calculations.

Experimental planning questions can hit 6 marks or more. Higher marks mean more detail needed in your answer.

The mark allocation tells you how much to write. One mark = one key point, roughly.

Final Thoughts

Hard Physics questions aren't there to trick you. They're there to test your understanding. Simple as that.

Every challenging question is a chance to show what you know. When you crack one, you prove you can think like a physicist. That's powerful.

The questions that seem impossible right now? With practice, they'll become routine. Seriously.

Here's what to do next: Start practising today. Work through past papers regularly. Learn from every mistake you make. Show all your working, every time. Use precise, scientific language.

Be patient with yourself. Nobody masters tough questions overnight. But with each one you practice, you get better. Stronger. More confident.

When you open that exam paper, you'll recognise exactly what to do. You'll have the strategies. You'll have the practice. You'll have the confidence.

Your hard work will absolutely pay off.

References

• Cambridge IGCSE Physics (0625) Specification (opens in a new tab)

• Edexcel IGCSE Physics (4PH1) Specification (opens in a new tab)

• Oxford AQA IGCSE Physics (9203) Specification (opens in a new tab)

• Cambridge IGCSE Physics, Paper 0625/22, March 2021 (opens in a new tab)

• Cambridge IGCSE Physics, Paper 0625/41, June 2023

• Edexcel IGCSE Physics, Paper 4PH1 1P, June 2022

• Edexcel IGCSE Physics, Paper 4PH1 1PR, June 2022

• Save My Exams IGCSE Physics Revision Notes

• Save My Exams IGCSE Physics Exam Questions

• Save My Exams Smart Mark

• Save My Exams Target Test

• Save My Exams IGCSE Physics Past Papers