IGCSE Physics: Thermal Properties and Temperature Practice Questions
Most substances expand when heated because their particles vibrate more and move slightly further apart. Specific heat capacity is the energy needed to raise the temperature of one kilogram of a substance by one degree Celsius.
Sub-topic 2.2 of Cambridge IGCSE Physics 0625 combines a calculation with several explanation questions. The specific heat capacity equation appears regularly, and heating curve explanations reuse the same reasoning as changes of state in Chemistry. The questions below cover both.
What you need to know for Thermal Properties and Temperature
- Thermal expansionHeating gives particles more energy so they vibrate more vigorously and occupy slightly more space. Gases expand most, then liquids, then solids.
- Applications and consequences of expansionExpansion gaps in bridges and railway lines, bimetallic strips in thermostats, and the rise of liquid in a thermometer all rely on it.
- Specific heat capacityThe energy required to raise the temperature of 1 kg of a substance by 1 degree Celsius. The equation is E = mc delta T, with energy in joules, mass in kilograms and c in J/(kg degree C).
- Melting and boilingDuring a change of state the temperature stays constant, because the energy supplied is used to overcome the forces of attraction between particles rather than to increase their average kinetic energy.
- ThermometersA liquid in glass thermometer uses the expansion of a liquid. Sensitivity is improved by a narrower bore, range by a wider bore or a larger bulb, and responsiveness by thinner glass and a smaller bulb.
- Water is unusualWater has a very high specific heat capacity, which is why it is used in central heating systems and as a coolant, and why coastal climates are less extreme.
IGCSE Physics Thermal Properties and Temperature questions and answers
4 exam-style questions written to the 0625 syllabus. Try each one on paper first, then open the worked answer to check your method against the marks.
Calculate the energy needed to raise the temperature of 2.5 kg of water from 20 degrees Celsius to 80 degrees Celsius. The specific heat capacity of water is 4200 J/(kg degree C).
Show the worked answer
- Use E = mc delta T.
- Temperature change delta T = 80 minus 20 = 60 degrees Celsius.
- E = 2.5 x 4200 x 60.
- E = 630000 J, which is 630 kJ.
Explain, in terms of particles, why a metal bar expands when it is heated.
Show the worked answer
- Heating transfers energy to the particles in the metal, increasing their average kinetic energy.
- The particles vibrate more vigorously about their fixed positions in the lattice.
- Vibrating through a larger amplitude means each particle occupies slightly more space, so the average separation between particles increases.
- Since every particle is slightly further from its neighbours, the bar as a whole becomes longer. The number and size of the particles themselves do not change.
A student heats a solid at a steady rate and plots temperature against time. The graph rises, then stays flat, then rises again. Explain the flat section.
Show the worked answer
- The flat section occurs at the melting point of the substance.
- Energy is still being supplied at a steady rate during this section.
- That energy is used to overcome the forces of attraction holding the particles in fixed positions in the solid lattice, allowing them to move past one another.
- Since the energy is not increasing the average kinetic energy of the particles, the temperature stays constant until all the solid has melted. The temperature then rises again.
A liquid in glass thermometer is redesigned with a narrower capillary tube. State the effect on its sensitivity and on its range, and explain each.
Show the worked answer
- A given expansion of the liquid must fill the tube. A narrower tube has a smaller cross sectional area, so the same volume of liquid produces a longer column.
- The liquid therefore moves further for each degree of temperature rise, so the thermometer is more sensitive and small changes are easier to read.
- However, the tube has a fixed length. Because the liquid moves further per degree, it reaches the top of the tube after a smaller temperature rise.
- The range of temperatures the thermometer can measure is therefore reduced. Sensitivity and range are always traded against each other in this design.
Common mistakes in this topic
- Using the final temperature instead of the temperature change in E = mc delta T.
- Saying particles expand when heated.
- Confusing specific heat capacity with the total energy required. Specific heat capacity is per kilogram per degree.
- Saying temperature rises during melting.
- Forgetting to convert grams to kilograms before using E = mc delta T.
Exam tips
- Write E = mc delta T and calculate delta T on its own line before substituting.
- For expansion questions, always mention that particle separation increases and particle size does not.
- For any flat section on a heating or cooling curve, name the change of state and say what the energy is doing.
- In thermometer questions, link every design change to sensitivity, range or responsiveness explicitly.
- Remember water's high specific heat capacity explains both its use as a coolant and milder coastal climates.
Practise 20 more questions like this, free
vStudyWise marks every answer instantly, tracks the topics you keep dropping marks on and turns them into a weekly study plan.
Thermal Properties and Temperature FAQs
What is specific heat capacity?
Specific heat capacity is the energy required to raise the temperature of one kilogram of a substance by one degree Celsius. The equation is E = mc delta T, where E is energy in joules, m is mass in kilograms, c is the specific heat capacity and delta T is the temperature change.
Why does the temperature stay constant during melting?
The energy being supplied is used to overcome the forces of attraction holding the particles in their fixed positions, allowing them to move past one another. It is not increasing the average kinetic energy of the particles, and temperature depends on that average kinetic energy, so the temperature does not change until melting is complete.
Why do solids expand when heated?
Heating increases the energy of the particles, so they vibrate more vigorously about their fixed positions. The larger vibrations mean each particle effectively occupies more space, so the average separation between particles increases and the solid expands. The particles themselves do not change size.
How can a thermometer be made more sensitive?
Use a narrower capillary tube, so a given expansion of liquid produces a longer column and a bigger movement per degree. A larger bulb also increases sensitivity by providing more liquid to expand. Both changes reduce the range, because the liquid reaches the top of the tube sooner.
Continue through the IGCSE Physics syllabus
Related IGCSE Physics topics
See all 24 IGCSE Physics practice topics ›
Written to the published Cambridge IGCSE Physics (0625) syllabus. Check your school entry code and syllabus year, because Core and Extended candidates are assessed on different content. Last reviewed 2026-08-12.