Brownian motion
Brownian
motion is quite easily detected by any small free moving objecs. The
size should be close to 1um to be able to see the fenomenon. The
movement of the particlels is directly related to the collisions of
individual atoms. Due to the distribution of the temperature to
each individual atom, the movmement will be randomized.
This phenomenon was one of the first direct evidence of the existence of atoms. It
is possible to calculate the size of the atoms, in this case
water molecules by the movement of the particle size, its
mass, and surrounding temperatur. However the math is not so straight
forvard and is quite complex.
Movie appr 4Mbyte. (It is easier to watch if you save the file on your hard disk first and open it in fullscreen mode)
A slurry of ceriumoxide polishing powder suspended in water. The larger particles are appr 5um in size the smallest wich are appr one single pixel are appr 0,5-1um. The smallest particles can easily seen bouncing around between the larger particles. A standard microscope was used to view the sample, and the movie was collected by a standard CCD camera.
Image from the movie. Polishing particles of different sizes. The
smallest particles can easily be seen moving around.
Movie appr 4Mbyte. (It is easier to watch if you save the file on your hard disk first and open it in fullscreen mode)
A slurry of ceriumoxide polishing powder suspended in water. The larger particles are appr 5um in size the smallest wich are appr one single pixel are appr 0,5-1um. The smallest particles can easily seen bouncing around between the larger particles. A standard microscope was used to view the sample, and the movie was collected by a standard CCD camera.
Image from the movie. Polishing particles of different sizes. The
smallest particles can easily be seen moving around.