Energy Transfer

Energy in the form of Heat can be transferred (moved) from one place to another.

   

Energy always moves from an energy source (high energy) to an energy sink (low energy).

   

Heat energy can move by

• Conduction
• Convection
• Radiation

     

  Conduction

     

  Definition: Conduction is the process where energy moves from high energy to low energy through contact (touching).

   

  Example: Demo - Touched paper to the hot can. The paper began to burn.

     

  Convection

     

  Definition: Convection is the process where energy moves from high energy to low energy by movement of gases or liquids.

     

  Example: Demo - Steam leaving the hot can.

     

  Radiation

     

  Definition: Radiation is the process of moving energy though transparent or translucent materials in a straight line.

     

  If material is opaque, it will block radiation. Materials can be opaque to some types of radiation, but transparent to others.

     

  Examples:

• Radio Waves can pass through walls.
• X-Rays can pass through flesh, but cannot pass through bone.
• Heat cannot pass through glass.

     

  Demo - Laser & holding the can over our hand (and blocked it with paper)

     

  Does heat rise?

     

  NO! Hot liquids or hot gases will rise due to density differences.

     

  Testable Concepts

  • Define Radiation
  • Define Conduction
  • Define Convection
  • Identify the dominant transfer method in a variety of situational descriptions.