Energy transfer

• Energy transfer by waves

  Waves are an energy transfer pathway
• Waves


  Involves oscillation or vibration in a field medium
• Sound waves


  Vibrations of particles
• Light waves


  Oscillation in the electric and magnetic field and are part of the electromagnetic spectrum.
• Best emitters and absorbers


  Matte black objects are the best emitters and absorbers of infrared radiation.
• Worst emitters and absorbers

  Shiny, white objects are the worst emitters and absorbers of infrared radiation
• Temperature


  The measure of how hot something is. We measure it in Celsius using a thermometer.
• Why does it take different amounts of energy to heat different substances?

  When a substance is heated, the energy of its particle increases.. The stronger the force between the particles in the substance, the more heat energy it takes to increase the kinetic energy of the particles, so the temperature rise is less than in substances with little force between particles.
• Specific heat capacity


  The amount of energy needed to raise the temperature of one kg of a substance by 1 Celsius
• Calculating specific heat capacity

  Change in energy x mass x change in temperature
• Conductors


  High thermal conductivity; used where we want energy to be transferred
• Insulators


  Low thermal conductivity; used where we don't want energy transferred
• Convection


  Heated particles in liquid and gases gain energy and move faster. This means they collide more often and with more energy; so they spread out. This makes the fluid less dense. The less dense fluid is displaced by colder more dense fluid making it rise taking the energy with it