Radiation & Absorption

• What is the aim of the investigation described?

  To investigate infrared radiation absorption and emission
• How does the amount of heat emitted or absorbed depend on a surface?

  It depends on the colour of the surface
• What device is used to measure heat emitted and absorbed?

  Leslie cube
• What is the independent variable in the experiment?

  Different faces of Leslie's cube
• What is the dependent variable in the experiment?

  The amount of heat emitted from each face
• What are the control variables in the experiment?

  Size and shape of Leslie's cube, initial temperature of water
• What type of radiation do hot objects emit?

  Heat in the form of radiation
• Why does the colour of a surface affect heat absorption and emission?

  Different colours absorb and emit heat differently
• What factors influence the heat emitted or absorbed by an object?

  Temperature and colour of the surface
• What is the focus of the practical described?

  Infrared absorption and emission
• What is the purpose of the matte black surface on the Leslie cube?

  To compare infrared emission with shiny surfaces
• What should be done to reduce heat loss during the experiment?

  Cap the Leslie cube after adding water
• How does the temperature of the shiny side compare to the matte black side?

  The matte black side is significantly hotter
• What does a higher temperature reading on the matte black side indicate?

  It emits more infrared radiation
• What type of lamp is used in the second experiment?

  Infrared lamp
• What materials are the copper tubes covered with in the second experiment?

  Shiny, matte white, and matte black materials
• Why should cotton wool be used around the thermometer in the tubes?

  To prevent contact with the tube sides
• What is the expected outcome when boiling tubes with different surfaces are exposed to infrared radiation?

  Matte black will have the highest temperature
• What is the relationship between surface type and infrared absorption?

  Matte black absorbs the most infrared
• What is the effect of shiny surfaces on infrared radiation?

  They are poor emitters and absorbers
• Why is a white T-shirt preferable on a sunny day?

  It absorbs less infrared radiation
• How does the performance of matte white surfaces compare to matte black and shiny surfaces?

  Matte white is intermediate in performance
• What is the temperature reading for the shiny side of the Leslie cube?

  35.1 °C
• What is the temperature reading for the matte black side of the Leslie cube?

  83.8 °C
• What happens to the temperature of water in the Leslie cube over time?

  It decreases due to heat loss
• What is the significance of using a heatproof mat in the experiment?

  To minimize heat loss through conduction