to count number of particles in colloidal dispersions
for stability of colloids
to determine charge on colloidal particles
to determine size of colloidal particles
Solution
Electrophoresis. When an electric current is passed through colloidal solution, the colloidal particles will move towards oppositely changed electrode, lose their charges and get coagulated. This process is called electrophoresis. The dispersion medium will also move towards oppositely charged electrode. Electrophoresis is used to determine charge on colloidal particles.