Search results
Results from the WOW.Com Content Network
The hole mobility is defined by a similar equation: =. Both electron and hole mobilities are positive by definition. Usually, the electron drift velocity in a material is directly proportional to the electric field, which means that the electron mobility is a constant (independent of the electric field).
is the mobility (m 2 /(V·s)). In other words, the electrical mobility of the particle is defined as the ratio of the drift velocity to the magnitude of the electric field: =. For example, the mobility of the sodium ion (Na +) in water at 25 °C is 5.19 × 10 −8 m 2 /(V·s). [1]
The formula for evaluating the drift velocity of charge carriers in a material of constant cross-sectional area is given by: [1] =, where u is the drift velocity of electrons, j is the current density flowing through the material, n is the charge-carrier number density, and q is the charge on the charge-carrier.
The rate of diffusion of each ion will be roughly proportional to its speed in an electric field, or their ion mobility. If the anions diffuse more rapidly than the cations , they will diffuse ahead into the dilute solution, leaving the latter negatively charged and the concentrated solution positively charged.
where D is the diffusion coefficient for the electron in the considered medium, n is the number of electrons per unit volume (i.e. number density), q is the magnitude of charge of an electron, μ is electron mobility in the medium, and E = −dΦ/dx (Φ potential difference) is the electric field as the potential gradient of the electric potential.
Electroosmotic flow is caused by the Coulomb force induced by an electric field on net mobile electric charge in a solution. Because the chemical equilibrium between a solid surface and an electrolyte solution typically leads to the interface acquiring a net fixed electrical charge, a layer of mobile ions, known as an electrical double layer or Debye layer, forms in the region near the interface.
Electrophoretic mobility is proportional to electrophoretic velocity, which is the measurable parameter. There are several theories that link electrophoretic mobility with zeta potential. They are briefly described in the article on electrophoresis and in details in many books on colloid and interface science.
where D is the diffusion constant, μ is the "mobility", k B is the Boltzmann constant, T is the absolute temperature, and q is the elementary charge, that is, the charge of one electron. Below, to combine in the same formula the chemical potential μ and the mobility, we use for mobility the notation m {\displaystyle {\mathfrak {m}}} .