Infrared Radiation

AQA GCSE Physics infrared radiation practical - investigating black body radiation of different surface types.‍ ‍Combined & Triple Science.

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A student investigates how different surfaces emit infrared radiation using a Leslie cube. The cube has the following four faces:

• Shiny Black

• Matt White

• Matt Black

• Shiny Silver

Describe a method to investigate how surface type affects infrared emission and explain how the student could present the results.

[6 marks]

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Prepare

• What equipment do we use?

  • A Leslie cube has 4 different surface types

    • shiny black

    • matt white

    • matt black

    • shiny silver

• How do we make it release infrared radiation?

  • Place it on a heatproof mat

  • Pour boiling water into it and close it

Measure & Record

• How do we measure infrared intensity?

  • Place an infrared detector at a set distance from one of the surfaces

  • Record the reading for that surface

  • Repeat for the other three surfaces

• What do we control (keep the same)?

  • Make sure the detector is always the same distance from and angle to the surface you’re measuring

  • The temperature should also be controlled by promptly taking readings from each surface (so that the cube's temperature changes as little as possible between measurements).

Plot

• What type of graph do we plot? (NO need to memorise the results!)

  • Since the independent variable (the surface type) is qualitative (words, not numbers), a bar chart would be suitable.

  • Plot infrared readings on the y-axis against the surface type on the x-axis.

Challenge

• What conclusion can be made from the results in the chart?

  Matt black surfaces are good emitters of infrared radiation, while shiny silver surfaces are poor emitters.

  The nature of a surface affects how much infrared radiation it emits at the same temperature.

Continue Revising Paper 2

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