one of the fundamental concepts underlying diffusion of particles is a phenomenon called Brownian motion also known as Brownian movement this is caused by the random motion of the medium that the particles are in for example water molecules will impinge on the larger particles causing them to move in random directions different properties of the medium can lead to differences in the observed Brownian movement for example if the temperature goes up the water molecules move faster and the particles will move faster as well conversely if the temperature goes down the water molecules move slower and the particles move slower if the molecules become larger for example if the medium is more viscous such as honey or tar the molecules and particles will move slower as well if we narrowed the width of the tube the particles come closer together and the dominant direction of motion is along the length of the tube this movement known as diffusion is the property we will be measuring with the software package mr tricks