P2: Energy transfer by heating

• P2 1) Which are better conductors: metals or non-metals?

  Metals
• P2 2) Which is a better conductor, copper or steel?

  Copper
• P2 3) The greater thermal conductivity....

  The more energy per second it transfers by conduction.
• P2 4) What is conduction?

  Transfer of heat through a solid.
• P2 5) What makes a good insulator?

  A material that has low thermal conductivity
• P2 6) How does the thickness of a material affect the rate of conduction through it?

  Thicker material the slower the rate of conduction through it
• P2 7) What is infrared radiation?

  all objects emit and absorb infrared radiation
• P2 8) The hotter the object, the more/less infrared radiation it emits in a given time?

  more
• P2 9) What is meant by black body radiation?

  radiation emitted by a body that absorbs all the radiation incident on it
• P2 10) What happens to the temperature of an object if it absorbs more radiation than it emits?

  increases
• P2 11) What happens to the temperature of an object f it absorbs more radiation than it emits?

  increases
• P2 12) How is the temperature of the Earth affected by the balance of absorbed and emitted radiation?
• P2 13) What is specific heat capacity?

  The energy needed to raise the temperature of 1kg of the substance by 1 degree Celsius.
• P2 14) What is the equation fir specific heat capacity?

  Energy transferred (J) = mass (kg) x specific heat capacity(J/kg/°C) x temperature change (°C)
• P2 15) What is the unit for specific heat capacity?

  J/kg °C
• P2 16) How does the mass of a substance affect how quickly its temperature changes when heating?

  The greater the mass of an object, the more slowly its temperature increases when it is heated.
• P2 17) How can you reduce the amount of energy lost from your home?

  Loft insulation, cavity wall insulation, aluminium foil between a radiator, double glazing windows, thicker walls.
• P2 18) How does loft insulation lower the amount of energy lost from your home?

  Reduces the rate of energy lost through the roof.
• P2 19) How does cavity wall insulation lower the amount of energy lost from your home?

  Reduces the rate of energy lost through the walls. It traps air in small pockets, reducing energy lost through conduction.
• P2 20) How does aluminium foil between a radiation reduce the amount of energy lost from your home?

  Reflects radiation away from the water, so reduces heat lost through radiation.
• P2 21) How does double glazed windows reduce the amount of energy lost from your home?

  Vacuum in between two glass panels prevents transfer of heat through conduction. Reduces amount of heat lost through windows.