Thermal processes cover how energy moves from hot to cold, what happens to materials when they are heated, and how to read a temperature-time graph. You explain nearly everything with the particle model, so a clear picture of moving particles is the real skill here.
Exact wording and required items change between syllabus years, so check the current Cambridge IGCSE Physics 0625 page for your exam year. This page follows the general skills. The Physics learning guide shows where the topic sits in the whole subject.
What do I need to know first?
You need the three states of matter and how their particles are arranged: close and fixed in solids, close and sliding in liquids, far apart and fast in gases. You also need to read a line graph. The calculations that use specific heat capacity belong to heat calculations, which comes next.
One worked example that uses the whole topic
A cup holds 0.25 kg of hot water that cools from 80 °C to 60 °C on a table. The specific heat capacity of water is given as 4200 J/(kg °C). (Invented example data.)
Energy lost: energy = mass × specific heat capacity × temperature change = 0.25 × 4200 × 20 = 1050 × 20 = 21 000 J.
How it leaves: the base passes energy to the table by conduction. Warm air and steam rise from the surface by convection. The cup also gives out infrared radiation in all directions.
How to slow it: a lid reduces convection and evaporation, a thick wall reduces conduction, and a shiny outer surface reduces radiation.
One small example already uses energy, three transfer processes and insulation. Later lessons separate them properly.
In what order should I study the lessons?
- Explain expansion using a particle model. It builds the picture of vibrating particles that everything else uses.
- Compare conduction, convection and radiation. Each process is explained by that same picture.
- Distinguish temperature from thermal energy. This clears up the word “heat” before graphs use it.
- Interpret a temperature-time graph. It needs the difference between temperature and energy, and a graph tool such as the graph-model and residual explorer helps.
- Explain insulation from a supplied structure. It combines every earlier lesson in one design question.
Then use the thermal processes practice set to test all five together.
What traps catch students?
- “Particles expand” instead of “particles move further apart”.
- “Heat rises” instead of “hot fluid is less dense, so it rises”.
- A flat graph line read as “no energy going in”.
- Saying the bigger object has the higher temperature because it has more energy.
- “A vacuum stops radiation”, when a vacuum only stops conduction and convection.
How do I use the practice set well?
Attempt it after the lessons, on paper, writing full sentences for explanation questions. Then compare with the worked answers. The set ends with a table that sends each error type back to the right lesson.
Explanation answers are easy to read as correct and still lose marks. Our teachers look at that in online one-to-one Physics tuition.