[[Image:Static7.png|thumb|270px| EM.Ferma's Navigation Tree.]]
The simplest static problems involve a charge source === Variety of Physical Objects in the free space that produces an electric field, or a current source in the free space that produces a magnetic field. In such cases, the only applicable boundary conditions are defined at the computational domain boundary. As soon as you introduce a dielectric object next to a charge source or a magnetic (permeable) material next to a current source, you have to deal with a complex boundary value problem. In other words, you need to solve the electric or magnetic Poisson's equation subject to the domain boundary conditions as well as material interface boundary conditions. EM.Ferma used the Finite Difference technique for numerical solution of your static boundary value problem. ===
=== A Note on Material and Source Types The simplest static problems involve a charge source in the free space that produces an electric field, or a current source in the free space that produces a magnetic field. In such cases, the only applicable boundary conditions are defined at the boundary of the computational domain. As soon as you introduce a dielectric object next to a charge source or a magnetic (permeable) material next to a current source, you have to deal with a complex boundary value problem. In other words, you need to solve the electric or magnetic Poisson equation subject to the domain boundary conditions as well as material interface boundary conditions. EM.Ferma ===uses the Finite Difference (FD) technique to find a numerical solution of your static boundary value problem.
In [[EM.Cube]]'s other modules, material types are specified under the "Physical Structure" section of the navigation tree, and sources are organized under a separate "Sources" section. In those modules, the physical structure and its various material types typically represent all the CAD objects you draw in your project. Sources are virtual entities that might be associated with certain physical objects and provide the excitation of your boundary value problem.  In EM.Ferma, materials and sources are all listed under the "Physical Structure" section of the navigation tree. In other words, there is no separate "Sources" section. For example, you can define default zero-potential perfect electric conductors (PEC) in your project to model metal objects. You can also define fixed-potential PEC objects with a nonzero voltage, which can effectively act as a voltage source for your boundary value problem. In this case, you will solve the Lapalce equation subject to the specified nonzero potential boundary values. Both offers six types of PEC objects are defined from the same PEC node of the navigation tree by assigning different voltage values. Charge and current sources are defined as CAD objects, and you have to draw them in the project workspace just like other material objects. === Grouping Objects by Material or Source Type === Your physical structure in EM.Ferma is typically made up of some kind of source either in the free space or in the presence of one or more material objects. EM.Ferma's electrostatic and magnetostatic simulation engines then discretize these source and material objects and solve the Laplace or Poisson equations to find the electric or magnetic fields everywhere in the computational domain.  All the CAD objects in the project workspace are organized together into object groups which share the same properties including color and electric or magnetic [[parameters]]. Once a new object group node has been created on the navigation tree, it becomes the "Active" object group of the project workspace, which is always listed in bold letters. When you draw a new CAD object such as a Box or a Sphere, it is inserted under the currently active surface type. There is only one object group that is active at any time. Any group can be made active by right clicking on its name in the navigation tree and selecting the '''Activate''' item of the contextual menu. It is recommended that you first create object groups, and then draw new objects under the active surface group. However, if you start a new EM.Ferma project from scratch, and start drawing a new object without having previously defined any object groups, a new default PEC object group is created and added to the navigation tree to hold your new CAD object. [[Image:Info_icon.png|40px]] Click here to learn more about '''[[Defining_Materials_in_EM.Cube#Defining_a_New_Material_Group | Defining a New Object Group]]'''. [[Image:Info_icon.png|40px]] Click here to learn more about '''[[Defining_Materials_in_EM.Cube#Moving_Objects_among_Material_Groups | Moving Objects among Different Groups]]'''. === Variety of Material Objects === [[Image:Static1.png|thumb|330px| EM.Ferma's PEC dialog.]] EM.Ferma offers the following types of material objects for construction of your physical structure (click on each type to learn more about it):
{| class="wikitable"
|-
! scope="col"| Material Physical Object Type
! scope="col"| Applications
! scope="col"| Geometric Object Types Allowed
! scope="col"| Notes & Restrictions
|-
| style="width:200px;" | '''[[Glossary of EM.Cube's Materials & Physical Object Types#Fixed-Potential PEC |Fixed-Potential Perfect Electric Conductor (PEC)]]'''
| style="width:300px;" | Modeling perfect metals with a fixed voltage
| style="width:250px;" | Solid and surface objects
| style="width:250px;" | Can be considered an electric source if the fixed voltage is nonzero
|-
| style="width:200px;" | '''[[Glossary of EM.Cube's Materials & Physical Object Types#Dielectric Material |Dielectric/Magnetic Material]]'''
| style="width:300px;" | Modeling any homogeneous material
| style="width:250px;" | Solid objects
| style="width:250px;" | non-source material
|-
| style="width:200px;" | '''[[Glossary of EM.Cube's Materials & Physical Object Types#Volume Charge |Volume Charge]]'''
| style="width:300px;" | Modeling volume charge sources with a fixed charge density or an expression in the global coordinates (x,y,z)
| style="width:250px;" | Solid objects
| style="width:250px;" | Acts as an electric source
|-
| style="width:200px;" | '''[[Glossary of EM.Cube's Materials & Physical Object Types#Volume Current |Volume Current]]'''
| style="width:300px;" | Modeling volume current sources with a fixed volume current density vector or expressions in the global coordinates (x,y,z)
| style="width:250px;" | Solid objects
| style="width:250px;" | Acts as a magnetic source
|-
| style="width:200px;" | '''[[Glossary of EM.Cube's Materials & Physical Object Types#Permanent Magnet |Permanent Magnet]]'''
| style="width:300px;" | Modeling permanent magnet sources with a fixed magnetization vector or expressions in the global coordinates (x,y,z)
| style="width:250px;" | Solid objects
| style="width:250px;" | Acts as a magnetic source
|-
| style="width:200px;" | '''[[Glossary of EM.Cube's Materials & Physical Object Types#Wire Current |Wire Current]]'''
| style="width:300px;" | Modeling wire current sources
| style="width:250px;" | line and polyline objects
| style="width:250px;" | Acts as a magnetic source
|}
Click on each category to learn more details about it in the [[Glossary of EM.Cube's Materials & Physical Object Types]].
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=== Grouping Objects by Material or Source Type ===
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Your physical structure in EM.Ferma is typically made up of some kind of source either in the free space or in the presence of one or more material objects. EM.Ferma's electrostatic and magnetostatic simulation engines then discretize these source and material objects and solve the Laplace or Poisson equations to find the electric or magnetic fields everywhere in the computational domain.
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All the CAD objects in the project workspace are organized together into object groups which share the same properties including color and electric or magnetic [[parameters]]. Once a new object group node has been created on the navigation tree, it becomes the "Active" object group of the project workspace, which is always listed in bold letters. When you draw a new CAD object such as a Box or a Sphere, it is inserted under the currently active surface type. There is only one object group that is active at any time. Any group can be made active by right clicking on its name in the navigation tree and selecting the '''Activate''' item of the contextual menu. It is recommended that you first create object groups, and then draw new objects under the active surface group. However, if you start a new EM.Ferma project from scratch, and start drawing a new object without having previously defined any object groups, a new default PEC object group is created and added to the navigation tree to hold your new CAD object.
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[[Image:Info_icon.png|40px]] Click here to learn more about '''[[Defining_Materials_in_EM.Cube#Defining_a_New_Material_Group | Defining a New Object Group]]'''.
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[[Image:Info_icon.png|40px]] Click here to learn more about '''[[Defining_Materials_in_EM.Cube#Moving_Objects_among_Material_Groups | Moving Objects among Different Groups]]'''.
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=== Variety of Material Objects ===
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[[Image:Static1.png|thumb|330px| EM.Ferma's PEC dialog.]]
EM.Ferma offers the following types of material objects for construction of your physical structure (click on each type to learn more about it):
</tr>
</table>
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=== A Note on Material and Source Types in EM.Ferma ===
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In [[EM.Cube]]'s other modules, material types are specified under the "Physical Structure" section of the navigation tree, and sources are organized under a separate "Sources" section. In those modules, the physical structure and its various material types typically represent all the CAD objects you draw in your project. Sources are virtual entities that might be associated with certain physical objects and provide the excitation of your boundary value problem.
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In EM.Ferma, materials and sources are all listed under the "Physical Structure" section of the navigation tree. In other words, there is no separate "Sources" section. For example, you can define default zero-potential perfect electric conductors (PEC) in your project to model metal objects. You can also define fixed-potential PEC objects with a nonzero voltage, which can effectively act as a voltage source for your boundary value problem. In this case, you will solve the Lapalce equation subject to the specified nonzero potential boundary values. Both types of PEC objects are defined from the same PEC node of the navigation tree by assigning different voltage values. Charge and current sources are defined as CAD objects, and you have to draw them in the project workspace just like other material objects.
=== Using Fixed-Potential PEC Objects as Voltage Sources ===