Physics

• INFRARED RADIATION is waves that radiate out from any warm object
• Infrared radiation is the only type of heat transfer that does not involve contact
• At absolute 0, the kinetic energy of particles is 0
• Absolute 0 = 0K = -278°C
• Surface


  • White - good absorber, good emitter

  Black - good absorber, good emitter

  Shiny - poor absorber, poor emitter
• Convection


  Particles can flow past one another

  Heated particles expand and become less dense

  Less dense hot particles rise and are replaced by denser cold particles

  Convection currents transfer heat from hot to cold areas

  Convection currents can be seen in volcanoes, lava lamps, etc.
• Liquids and gases expand when heated
• Liquids and gases move faster when heated so take up more space
• Liquid or gas in hot areas is less dense than in cold areas
• Convection currents transfer heat from place to place
• Convection - Particles


  1.The fluid particles are heated

  2. The particles gain kinetic energy and vibrate more

  3. The space between particles increases, so the density decreases

  4. The low density hot particles rise and are replaced by cold dense particles

  5. The cold particles are now heated, so they rise making a continuous convection current
• Convection - Substances

  1. The fluid is heated

  2. The density of the hot fluid decreases

  3. The hot low density fluid rises and is replaced by cold dense fluid

  4. The cold fluid is now heated, so it rises making a convection current
• Expansion


  Solids expand when heated due to increased space between particles
• Contraction


  Solids contract when cooled due to decreased space between particles
• Conduction

  Heated particles pass energy to neighbouring particles by collision
• Conduction in metals

  • Electrons in metals can move freely and carry thermal energy

  Collisions between electrons and metal ions heat up the metal