Energy transfer by heating

• Entry Level Certificate
• Learning objectives include knowing which materials are the best conductors and insulators, how thermal conductivity affects the rate of energy transfer, and how thickness of walls affects the rate of energy transfer
• Thermal conductivity


  A measure of how quickly energy is transferred by conduction through a material
• Investigating different materials as insulators

  1. Put a small beaker inside a larger beaker

  2. Pour 100 ml hot water into the small beaker

  3. Use cardboard as a lid with a hole for a thermometer

  4. Record the temperature and start the stopwatch

  5. Record the temperature every 3 minutes for 15 minutes

  6. Repeat using different materials
• The slower the water cools down, the better the material is as an insulator
• Investigating the effect of thickness of insulators

  1. Put 100 ml hot water into a small beaker

  2. Add a lid with a small hole for the thermometer

  3. Record the temperature and start the stopwatch

  4. Record the temperature every 3 minutes for 15 minutes

  5. Repeat with two layers of insulating material
• The thicker the insulation, the slower the water will cool
• Insulating material being fitted in a loft has a low thermal conductivity
• Several layers of insulation reduce the heat energy transferred through the roof and keep the house warm in winter
• Houses are designed with walls that have low thermal conductivity
• Older houses often have very thick walls to help reduce the transfer of energy by heat
• Materials that are good conductors

  • copper
  • iron
• Materials that are good insulators

  • plastic
  • wool
• Good conductors have high thermal conductivity
• Good insulators have low thermal conductivity
• Adding more layers of an insulating material reduces energy transfer by heating
• A student is investigating two materials to find out which is the better insulator
• The temperature of the felt-covered beaker fell by 15°C and the temperature of the polystyrene-covered beaker fell by 10°C
• Better insulator


  The material that causes the least temperature change
• Highest thermal conductivity


  The material that causes the greatest temperature change