cool down asymptotically towards $0\\text{ K}$ rather than leveling off at $300\\text{ K}$.","order":2},{"id":"5748e9bd-af06-428c-88fe-0e966b5a9349","content":"The temperature of the chamber walls is $300\\text{ K}$. Sphere $P$ continues to emit more thermal radiation per second than sphere $Q$ because its initial temperature was higher.","correct":false,"markscheme":"Incorrect. Thermal emission depends on current temperature, not historical initial conditions. Once equilibrium is reached, historical temperatures do not dictate emission rates.","order":3}],"explanation":null,"firstAttemptFullMarks":null},{"id":"e40a39c7-f19b-436b-9826-5a8531b313cb","revisionId":"ab116d93-b513-4308-a686-560676d33b48","questionNumber":null,"questionType":"LA","specification":"Figure 1 shows some apparatus.\n\n![An infrared radiant heater positioned next to three identical glass boiling tubes. One tube is wrapped in matte black paper, one is wrapped in white paper, and one is wrapped in shiny aluminium foil. Each tube has a rubber bung with a hole holding a thermometer.](https://assets.mathsgenie.co.uk/aqa-qb/1fe82458-2cbb-4e7a-bd55-d189199adc41.png)","difficulty":5,"difficultyBand":null,"totalMarks":6,"sourceTitle":null,"calculatorUse":null,"parts":[{"id":"8be15de2-5ce5-42da-9fcc-9bf029622c6c","label":null,"content":"Describe an investigation to find out how the nature of a surface affects the rate at which it absorbs thermal radiation.\n\nYou should use the apparatus shown in Figure 1 and any additional standard laboratory equipment you need.","markscheme":"- Describes filling each of the three boiling tubes with the same volume of water (e.g., measured using a measuring cylinder) M1\n- States that all three tubes must be positioned at the same distance from the central infrared heater to control radiation intensity M1\n- Describes measuring and recording the initial (starting) temperature of the water in each tube M1\n- Describes switching on the heater and measuring the temperature of each tube at regular time intervals (e.g., every 60 seconds) for a total duration (e.g., 10 minutes) M1\n- Calculates the temperature change for each tube (final temperature minus initial temperature) M1\n- Concludes that the surface with the greatest temperature rise (matte black) is the best absorber of thermal radiation, and the one with the smallest temperature rise (shiny aluminium foil) is the poorest absorber A1","marks":6,"order":0,"markingRubric":null,"explanation":{"methods":[{"id":"controlled_heating","label":"Controlled heating comparison","steps":[{"type":"text","order":0,"title":"Measure equal water volumes","content":"Use a measuring cylinder to put the same measured volume of water into each boiling tube.\n\n[M1] Same measured volume of water in each tube.","highlights":[{"text":"any additional standard laboratory equipment you need","location":"specification"}]},{"type":"text","order":1,"title":"Match the distances","content":"Place all three tubes at the same distance from the central infrared heater. This keeps the intensity of thermal radiation reaching each surface the same.\n\n[M1] Same distance from the heater.","highlights":[{"text":"nature of a surface","location":"specification"}]},{"type":"text","order":2,"title":"Record starting temperatures","content":"Before switching on the heater, read and record the initial temperature of the water in every tube.\n\n[M1] Initial temperature recorded for each tube.","highlights":[{"text":"rate at which it absorbs thermal radiation","location":"specification"}]},{"type":"text","order":3,"title":"Heat and record","content":"Switch on the infrared heater. Record the temperature of every tube every 60 seconds for 10 minutes (600 seconds). Compare readings taken at the same times.\n\n[M1] Temperatures recorded at regular intervals for a stated total duration.","highlights":[{"text":"use the apparatus shown in Figure 1","location":"specification"}]},{"type":"hyper_latex","block":{"nodes":[{"latex":"\\Delta T

Thermal radiation and energy balance Solutions