GCSE Physics resources
AQA GCSE Waves
Investigate how the infrared radiation absorbed or emitted by a surface depends on that surface. Keep surface area, distance, starting temperature and timing controlled, repeat readings and compare rate of temperature change or detector response.
Start here
Investigate how the infrared radiation absorbed or emitted by a surface depends on that surface. Keep surface area, distance, starting temperature and timing controlled, repeat readings and compare rate of temperature change or detector response.
Before you revise
Choose an answer from memory. Your result tells you what to watch for in the guide.
Core revision guide
Infrared Absorption and Emission Required Practical questions become manageable when the central model, evidence and exam method are kept together. Read the explanation, test the misconception and then apply the idea without looking back.
Investigate how the infrared radiation absorbed or emitted by a surface depends on that surface. Keep surface area, distance, starting temperature and timing controlled, repeat readings and compare rate of temperature change or detector response.
Dull black surfaces absorb and emit infrared radiation well; shiny, light surfaces are poorer absorbers and emitters. Compare like-for-like surfaces, control distance and starting temperature, repeat readings, and base the conclusion on detector response or rate of temperature change.
Misconception clinic
Read each belief, say what is wrong with it, then compare your correction.
Tempting idea: Calling infrared “heat” rather than radiation.
Use instead: Investigate how the infrared radiation absorbed or emitted by a surface depends on that surface. Keep surface area, distance, starting temperature and timing controlled, repeat readings and compare rate of temperature change or detector response.
Tempting idea: Changing surface finish and distance together.
Use instead: Dull black surfaces absorb and emit infrared radiation well; shiny, light surfaces are poorer absorbers and emitters. Compare like-for-like surfaces, control distance and starting temperature, repeat readings, and base the conclusion on detector response or rate of temperature change.
Tempting idea: Treating this required practical as nuclear radiation.
Use instead: State the infrared source or detector, independent and control variables, repeated measurements, data comparison and a conclusion about dull black and shiny surfaces.
Retrieval practice
Worked examples
These examples expose the difference between a secure compare infrared surfaces fairly method and the common error “Calling infrared “heat” rather than radiation.”.
The dull black surface warms faster because it absorbs more infrared radiation than the shiny surface.
The dull black can cools faster because it is a better emitter of infrared radiation.
Infrared intensity at the detector changes with distance, so all surfaces must be measured at the same distance.
Exam precision
Do this: State the infrared source or detector, independent and control variables, repeated measurements, data comparison and a conclusion about dull black and shiny surfaces.
Independent practice
Write an answer before opening the marking guidance. Then edit the exact phrase or step that would gain the next mark.
Marking guidance: Award one mark for the precise statement shown in the model answer.
Model answer: Dull black.
Marking guidance: Award one mark for the precise statement shown in the model answer.
Model answer: Dull black.
Marking guidance: Award one mark for the precise statement shown in the model answer.
Model answer: The surface finish/colour.
Marking guidance: 2 marks are available for relevant, linked physics points that match the model answer.
Model answer: For example, initial temperature, distance, surface area, timing and lamp power.
Marking guidance: Award up to 3 marks for distinct physics points joined into a clear cause-and-effect chain.
Model answer: It reflects more infrared radiation and absorbs less.
Marking guidance: 2 marks are available for relevant, linked physics points that match the model answer.
Model answer: Repeat readings for each surface and calculate a mean, keeping geometry controlled.
Questions pupils ask
Investigate how the infrared radiation absorbed or emitted by a surface depends on that surface. Keep surface area, distance, starting temperature and timing controlled, repeat readings and compare rate of temperature change or detector response.
Calling infrared “heat” rather than radiation. Dull black surfaces absorb and emit infrared radiation well; shiny, light surfaces are poorer absorbers and emitters. Compare like-for-like surfaces, control distance and starting temperature, repeat readings, and base the conclusion on detector response or rate of temperature change.
Useful next steps