Required Practical: Radiation and Absorption

This lesson covers the Required Practical on investigating how the amount of infrared radiation absorbed or radiated by a surface depends on the nature of that surface, as required by the AQA GCSE Physics specification (4.6.2). This practical investigates the link between surface colour/texture and the emission and absorption of infrared radiation.

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Overview

AQA requires you to investigate the emission and absorption of infrared radiation by different surfaces. The key finding is:

• Dark, matt (rough) surfaces are good absorbers and good emitters of infrared radiation.
• Light, shiny (smooth) surfaces are poor absorbers and poor emitters of infrared radiation (they are good reflectors instead).

This practical can be examined in multiple ways: you may be asked to describe the method for emission, absorption, or both. You must also be able to identify variables, explain sources of error, and interpret results.

Exam Tip: This is a commonly examined required practical. Remember the key conclusion: dark matt surfaces are better emitters and absorbers of infrared radiation than light shiny surfaces. You should be able to describe both the emission and absorption experiments clearly.

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Experiment 1: Investigating Infrared Emission

Equipment