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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

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The correct answer is A. This question tests the candidate's understanding of ideal gases within the Physicssyllabus. The examiner's mark scheme requires...

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About This A-Level Physics Question

This multiple-choice question appeared in the Cambridge A-Level Physics (9702) Oct/Nov 2011 examination, Paper 1 Variant 2. It tests the topic of Ideal gases and is worth 1 mark.

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