Electrical Mobility

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ID:(1527, 0)



Electrical Mobility

Description

Variables

Symbol
Text
Variable
Value
Units
Calculate
MKS Value
MKS Units
$r$
r
Radius of a sphere
m
$v$
v
Speed
m/s
$F_v$
F_v
Viscose force
N
$\eta$
eta
Viscosity
Pa s

Calculations


First, select the equation:   to ,  then, select the variable:   to 

Symbol
Equation
Solved
Translated

Calculations

Symbol
Equation
Solved
Translated

 Variable   Given   Calculate   Target :   Equation   To be used



Equations


Examples

The resistance is defined in terms of the fluid viscosity and the sphere's velocity as follows:

$ F_v = b v $



Stokes explicitly calculated the resistance experienced by the sphere and determined that viscosity is proportional to the sphere's radius and its velocity, leading to the following equation for resistance:

$ F_v =6 \pi \eta r v $

(ID 4871)

A charged particle q in an electric field \ vec {E} means that a force equal to

$ F = q E $



This force is opposed by a force due to the effect of the medium that can be modeled by Stokes law

$ F_v =6 \pi \eta r v $



If both forces are equalized, it is obtained that the particle moves with a constant speed equal to

$ \vec{v} = \mu \vec{E} $



with mobility equal to

$ \mu =\displaystyle\frac{ q }{6 \pi \eta a }$

(ID 11997)

To equalize the force caused by the electric field

$ F = q E $



with the opposing force that is modeled with Stokes law

$ F_v =6 \pi \eta r v $



the relationship is obtained

$ \vec{v} = \mu \vec{E} $



with mobility equal to

$ \mu =\displaystyle\frac{ q }{6 \pi \eta a }$

(ID 11998)


ID:(1527, 0)