Practical 10 physics

• Measuring the absorbance of infrared by different surfaces

  Use an infrared heater with two metal plates painted with different paints, attach a drawn pin with Vaseline on each plate, switch on the heater and time the temperature increase, record the time it takes for the drawn pin to fall off
• Matte black surface emits the most infrared radiation, followed by shiny black surface, white surface, and shiny metallic surface emits the least infrared radiation
• Lesley's cube surfaces

  • Shiny metallic surface
  • White surface
  • Shiny black surface
  • Matte black surface
• Investigating how much infrared radiation is absorbed or radiated by different surfaces


  Fill Lesley's cube with hot water, point an infrared detector at each of the four surfaces, record the amount of infrared emitted, keep the same distance between the Lesley's cube and the infrared detector for repeatability
• Matte black surfaces absorb more infrared than shiny metallic surfaces
• Matte black surfaces


  Are better at emitting and absorbing infrared compared to shiny metallic surfaces
• Using a thermometer to measure absorbance of infrared may have lower resolution compared to an infrared detector