Compare with effusion . The ability of a wave to bend around the edges of obstacles or holes. The effect is most noticeable when the obstacle or hole is comparable to the size of the wavelength . Compare with effusion . The mixing of two substances caused by random molecular motions.
Molecular collisions make diffusion slower in liquids and solids.
Compare with effusion . The number of randomly moving molecules that pass through a unit area per second. Diffusion rates are fastest when a large concentration difference exists on either side of the unit area. Diffusion rates increase with temperature, and decrease with increasing pressure, molecular weight, and molecular size. A device for measuring volume changes.