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2.3 Transfer of thermal energy

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Question 39

Which of the following statements best explains why convection currents form in a fluid when it is heated?

A

The fluid expands when heated, making it less dense than the surrounding cooler fluid.

B

The individual molecules of the fluid expand when heated, making them lighter.

C

The fluid contracts when heated, making it denser than the surrounding cooler fluid.

D

High-energy molecules escape from the surface of the fluid, pulling cooler molecules upward.

Markscheme

2.3 Transfer of thermal energy Questions

  1. IGCSE
  2. /Physics
  3. /2.3 Transfer of thermal energy

301 exam-style questions on CIE IGCSE Physics 2.3 Transfer of thermal energy, covering 2.3.1a Thermal conductors and thermal insulators, 2.3.1b Explaining thermal conduction, 2.3.2 Convection, 2.3.3a Thermal radiation, 2.3.3b Surface colour and texture, 2.3.3c Rate of emission and absorption of radiation, and 2.3.4 Consequences of thermal energy transfer. Each one has a worked solution and a mark scheme showing where the marks go.

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