Required Practical 10:Infared

• What is the purpose of the practical described in the video?

  To investigate infrared radiation absorption and emission
• Why can't the human eye see infrared radiation?

  Infrared radiation is outside the visible spectrum
• What is a Lesley's cube used for?

  To measure infrared emission from surfaces
• What surfaces are present on a Lesley's cube?

  Shiny metallic, white, shiny black, matte black
• What is the first step in using a Lesley's cube for the experiment?

  Fill the cube with hot water
• Why is it important to keep the same distance between the Lesley's cube and the infrared detector?

  To ensure repeatable measurements
• Which surface emits the most infrared radiation?

  Matte black surface
• Which surface emits the least infrared radiation?

  Shiny metallic surface
• What can be used if an infrared detector is not available?

  A thermometer with a black bulb
• What is the resolution of a thermometer compared to an infrared detector?

  The thermometer has lower resolution
• What equipment is used to measure infrared absorbance?

  An infrared heater and metal plates
• What happens to the temperature of the metal plates during the experiment?

  The temperature increases as they absorb infrared
• What is used to attach the drawn pin to the metal plates?

  Vaseline
• What indicates that the matte black plate absorbs more infrared?

  The drawn pin falls off first
• What is the relationship between shiny metallic surfaces and infrared radiation?

  They reflect infrared radiation
• What are the key findings of the infrared radiation experiment?

  • Matte black surfaces emit and absorb more infrared
  • Shiny metallic surfaces emit and absorb less infrared
  • Infrared detectors are more sensitive than thermometers
• What are the steps to investigate infrared radiation using a Lesley's cube?

  1. Fill the Lesley's cube with hot water
  2. Point an infrared detector at each surface
  3. Record the infrared emitted from each surface
  4. Ensure consistent distance for repeatability
• What are the differences between matte black and shiny metallic surfaces in terms of infrared?

  • Matte black: absorbs and emits more infrared
  • Shiny metallic: reflects infrared and emits less