radiation and absorption

• Investigating how much infrared radiation is absorbed or radiated by different surfaces

  1. Fill Lesley's cube with hot water

  2. Point infrared detector at each surface

  3. Record amount of infrared emitted

  4. Keep same distance between Lesley's cube and detector
• Lesley's cube


  • Has 4 different surfaces: shiny metallic, white, shiny black, matte black
• Matte black surface


  Emits the most infrared radiation
• Shiny metallic surface


  Emits the least infrared radiation
• Thermometer


  Can be used if no infrared detector available, but has lower resolution
• Measuring absorbance of infrared by different surfaces

  1. Use infrared heater and metal plates

  2. One plate painted shiny metallic, other painted matte black

  3. Attach drawn pins to plates with Vaseline

  4. Switch on heater and time how long it takes for Vaseline to melt and pins to fall off
• Matte black plate


  Absorbs more infrared, pins fall off first
• Shiny metallic surface


  Reflects infrared instead of absorbing
• Matte black surfaces are much better at emitting and absorbing infrared than shiny metallic surfaces