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Practice questions · Everyday applications

Speed one up, slow the others down.

Six original Cambridge-style questions putting conduction, convection and radiation together: the vacuum flask, cooking pans, radiators, how fire spreads, and why trapped air insulates a home.

Original questions All questions on this page are original work, written in the Cambridge IGCSE style. They are not from past papers. They test the same concepts and skills the syllabus rewards.
Match each feature to a transfer

Name the transfer, then the design that controls it.

01
Analysis
[2 marks]

A saucepan has a metal base and a plastic handle. Explain why these two materials are chosen.

  • The metal base is a good conductor, so energy passes quickly to the food. ✓
  • The plastic handle is a poor conductor (insulator), so it stays cool enough to hold. ✓
02
Analysis
[3 marks]

A vacuum flask keeps a drink hot. Explain how its design reduces heat loss by conduction, by convection, and by radiation.

  • Conduction: the vacuum between the walls has almost no particles, so it cannot conduct. ✓
  • Convection: there is no air in the vacuum to form convection currents, and the stopper seals the top. ✓
  • Radiation: the silvered walls are poor emitters and reflect radiation back, reducing radiation loss. ✓
03
Analysis
[3 marks]

A heating radiator is fixed near the floor of a room. Explain how it warms the whole room, and why a low position helps.

  • Air heated at the radiator expands, becomes less dense and rises. ✓
  • Cooler air sinks to replace it, setting up a convection current that circulates warm air around the room. ✓
  • A low position lets the warmed air rise through the whole room; placed high, the warm air would stay trapped at the top. ✓
04
Analysis
[3 marks]

Explain how a fire in a building can spread by each of the three methods of thermal energy transfer.

  • Radiation: infrared crosses gaps and heats nearby objects until they catch alight. ✓
  • Convection: hot gases rise and carry energy upward, spreading fire to higher levels. ✓
  • Conduction: energy passes along metal beams, pipes and other materials to other rooms. ✓
05
Analysis
[2 marks]

Loft insulation is made of a thick, fluffy material that traps air. Explain how trapped air reduces heat loss from a house.

  • Air is a poor conductor, so trapped air greatly reduces heat loss by conduction. ✓
  • Because the air is trapped and cannot move freely, it also cannot set up convection currents. ✓
06
Analysis
[2 marks]

Energy from the Sun reaches the Earth across empty space. State which method of thermal energy transfer is responsible, and explain why it must be that one.

  • It must be radiation. ✓
  • Space is a vacuum with no particles, and only radiation can transfer energy without a medium; conduction and convection both need a material. ✓

Mark this once you have attempted all six and checked your working. It records a Practiced badge on the topic and adds a one-time bonus. Revealing the solutions alone does not count.