Home / Examples / Electric Analysis [Coulomb] / Example 6: Electric Field Created by Spherical Charge
In this example, a spherical charge is placed in the air.
The electric field generated by it is solved and the equipotential map is acquired.
Unless specified in the list below, the default conditions will be applied.
Results will vary depending on Femtet version and the PC environment.
Item |
Settings |
Analysis Space |
3D |
Model Unit |
mm |
Select [Static Analysis] as the electric potential is static.
Item |
Settings |
Solver |
Electric Analysis [Coulomb] |
Analysis Type |
Static Analysis (Capacitance) |
Options |
N/A |
Ambient air scale in this example is a bit larger than the default setting.
Tab |
Setting Item |
Settings |
Mesh Tab |
Ambient Air Creation |
Create ambient air automatically: Select Ambient Air Scale: 5.0 |
In actuality, the electric field exists outside the analysis domain. Therefore the open boundary condition below is applied initially.
Tab |
Setting Item |
Settings |
Open Boundary Tab |
Type |
Absorbing boundary |
Order of Absorbing Boundary |
1st order |
A sphere to represent the spherical charge is placed inside the cube.
Body Number/Type |
Body Attribute Name |
Material Name |
1/Solid |
Sphere |
000_Air(*) |
* Available from the material DB
Charge is set in the body attribute.
Body Attribute Name |
Charge |
Sphere |
Charge Density: Electric Charge ×10-3 [C/m3] |
Boundary Condition Name/Topology |
Tab |
Boundary Condition Type |
Settings |
Outer Boundary Condition * |
Electric |
Open Boundary |
|
To set Outer Boundary Condition, go to the [Model] tab
and click [Outer Boundary Condition] 
.
[Results]
The figure below shows the gradation contour of the electric potential on the Z=0 plane.
The electric potential map around the charge is well presented visually.
The electric potential at the spherical center is the highest.