A-LevelPhysicsIdeal gasesOct/Nov 2011Paper 1 Q191 Mark
In an experiment to demonstrate Brownian motion, smoke particles in a container are illuminated by a strong light source and observed through a microscope. The particles are seen as small specks of light that are in motion. What causes the Brownian motion?
Acollisions between the smoke particles and air molecules
Bcollisions between the smoke particles and the walls of the container
Cconvection currents within the air as it is warmed by the light source
Dkinetic energy gained by the smoke particles on absorption of light
✓ Correct Answer
The correct answer is A: collisions between the smoke particles and air molecules
📋 Examiner Report & Trap Analysis
Common mistake: 62% of candidates selected the distractor because they confused... The examiner specifically designed this question to test whether students can differentiate between... To secure full marks, candidates must demonstrate...
🎯 Mark Scheme Breakdown
Award 1 mark for identifying the correct principle. Award 1 mark for showing clear working. Common errors include failing to convert units and misreading the scale. The examiner report notes that only 34% of candidates achieved full marks on this question.
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