Brownian motion can be observed when looking at pollen grains suspended in water under a microscope. What causes the pollen grains to move in this random, jerky manner?
The pollen grains are hit by rapidly moving, invisible water molecules.
The pollen grains are carried by convection currents in the water.
The pollen grains actively swim through the water.
The pollen grains occasionally collide with the walls of the container.
151 exam-style questions on CIE IGCSE Physics 2.1.2a Particle structure and motion in solids, liquids and gases. Each one has a worked solution and a mark scheme showing where the marks go.