Conduction and Convection

• What are the two main processes of energy transfer by heating?

  Conduction and convection
• Why is it important to know about conduction and convection?

  To understand energy transfers by heating
• In which state of matter does conduction mainly occur?

  Solids
• What is conduction?

  Vibrating particles transfer energy to neighboring particles
• How is energy transferred to an object by heating?

  It is transferred to the thermal store of the object
• How is energy shared in an object being heated?

  Across the kinetic energy stores of the particles
• What happens to particles in the part of the object being heated?

  They vibrate more and collide with each other
• What is thermal conductivity?

  A measure of how quickly energy is transferred
• In which states of matter does convection occur?

  Liquids and gases
• What is convection?

  Energetic particles move from hotter to cooler regions
• What happens to particles in a heated liquid or gas?

  They move faster and the space between them increases
• What effect does heating have on the density of a liquid or gas?

  The density decreases in the heated region
• What can be created if there is a constant heat source in a liquid or gas?

  A convection current
• How does a radiator create convection currents?

  By transferring energy to nearby air particles
• What happens to the air near the radiator?

  It becomes warmer and less dense
• What occurs to the warm air after it rises?

  It is replaced by cooler air
• What happens to the cooler air in the room?

  It is heated by the radiator
• What happens to previously heated air as it transfers energy?

  It cools, becomes denser, and sinks
• Describe the process of convection currents created by a radiator.

  • Energy transferred from radiator to air by conduction
  • Air near radiator warms and becomes less dense
  • Warm air rises, replaced by cooler air
  • Cooler air is heated by the radiator
  • Heated air transfers energy to surroundings and sinks
  • Cycle repeats, creating convection currents
• Why is understanding conduction and convection useful?

  It helps explain how to stop unwanted transfers
• What is the name of the effect where energy is transferred through a solid by heating?

  Conduction
• What is the role of collisions in conduction?

  They transfer energy between particles' kinetic energy stores
• What happens to the energy transferred to the thermal store of an object?

  It is shared across the kinetic energy stores
• How does the process of conduction differ from convection?

  Conduction involves vibrating particles, convection involves moving particles
• What happens to the thermal energy of the surroundings when energy is transferred from an object?

  It increases as energy is transferred
• What is the effect of heating on the kinetic energy of particles in a solid?

  The kinetic energy of particles increases
• How does the density of a heated region in a liquid or gas affect its movement?

  Less dense regions rise above denser regions