Thermal energy transfers

• What is the formula for density?

  Density = mass/volume
• What happens to the density of ice when it changes from solid to liquid?

  The density decreases
• What happens to the kinetic energy of molecules when heat is added?

  It stays the same
• What happens to the internal energy of a substance when it is given heat?

  Its temperature increases
• What happens to the internal energy of a liquid when it expands?

  It increases
• What is specific latent heat?

  Energy to change 1kg from one state to another
• What is specific latent heat of fusion?

  Energy to change 1kg from solid to liquid
• What is specific latent heat of vaporisation?

  Energy to change 1kg from liquid to gas
• What is the name of the process that does not transfer energy?

  Conduction
• Why are metals good thermal conductors?

  They have free, delocalised electrons
• What is the opposite of a thermal conductor?

  A thermal insulator
• What two factors affect the rate of thermal energy transfer?

  Thermal conductivity of material and thickness
• What is thermal conductivity?

  The rate at which a material conducts heat
• What do most good insulating materials have in common?

  They contain trapped air
• How can a homeowner reduce heat loss from their home?

  Loft insulation, double glazing, cavity wall insulation
• What is pay-back time?

  Time taken for savings to cover costs
• What are the 7 groups of the electromagnetic spectrum?

  • Radio
  • Microwaves
  • Infra-red
  • Visible
  • Ultraviolet
  • X-rays
  • Gamma rays
• What do all electromagnetic waves have in common?

  They are transverse and travel at the same speed
• Which part of the electromagnetic spectrum has the longest wavelength?

  Radio
• Which part of the electromagnetic spectrum has the lowest frequency?

  Radio
• Which part of the electromagnetic spectrum is just beyond the red end of the visible spectrum?

  Infrared
• Which colour surface emits the most radiation?

  Matt black
• Which colour surface emits the least radiation?

  Shiny silver
• Which colour surface absorbs the most radiation?

  Matt black
• Which colour surface absorbs the least radiation?

  Shiny silver
• How does the temperature of an object affect the intensity of the radiation it gives out?

  The higher the temperature, the higher the intensity
• How does the temperature of an object affect the frequency of the radiation it gives out?

  The higher the temperature, the higher the peak frequency
• How does absorption and emission of radiation affect the temperature of an object?

  If absorption is higher than emission, temperature increases