A student places a microscope slide containing a drop of highly diluted milk under a high-power microscope. When looking through the eyepiece, they observe many tiny fat droplets suspended in water, which appear as small, bright dots.
Describe the motion of these fat droplets.
Explain, in terms of molecules, how this motion is caused.
Because the microscope has a very shallow depth of field, describe what is observed under the microscope when a fat droplet moves vertically (either towards or away from the objective lens).
321 exam-style questions on CIE IGCSE Physics 2.1 Kinetic particle model of matter, covering 2.1.1 States of matter and changes of state, 2.1.2a Particle structure and motion in solids, liquids and gases, 2.1.2b Gas pressure and particle collisions, 2.1.2c Brownian motion, 2.1.3a The absolute scale of temperature, and 2.1.3b Pressure, volume and temperature of a gas. Each one has a worked solution and a mark scheme showing where the marks go.