Energy Transfers & Particle MotionOxford AQA IGCSE Physics: Flashcards

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How does conduction transfer energy through a material?

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How does conduction transfer energy through a material?: By particle collisions, passing kinetic energy from particle to particle.
Why are metals good conductors of energy?: They contain free electrons that move through the structure and carry energy quickly.
What is convection?: The transfer of energy in a fluid where warmer, less dense fluid rises above cooler, denser fluid.
Why can't convection happen in a solid?: Particles in a solid cannot move freely enough to circulate and form a convection current.
Define evaporation.: Particles with the highest kinetic energy escaping from the surface of a liquid to become a gas.
Name two factors that increase the rate of evaporation.: Any two of: higher temperature, larger surface area, air movement over the surface, lower humidity.
Does evaporation only happen at boiling point?: No — evaporation can happen at any temperature, at the surface of a liquid.
What three factors affect the rate of energy transfer by heating an object?: Surface area and volume, the material of the object, and the nature of its surface.
How does temperature difference affect the rate of energy transfer?: The greater the temperature difference between an object and its surroundings, the faster the rate of energy transfer.
Why do cooling fins help prevent overheating?: They increase surface area, speeding up the rate of energy transfer to the surroundings.
Why might a desert animal have large ears?: Large ears increase surface area relative to volume, helping the animal lose energy faster to stay cool.
What happens to most substances when they are heated?: They expand, which is used in bi-metallic strip thermostats but can also cause hazards like buckling roads or bridges.