Changes

Before you draw a spherical charge object, you have to create a charge object category on the navigation tree. In [[EM.Ferma]], objects are grouped together and organized by their static behavior under the “Physical Structure” node of the navigation tree. There are several categories to choose from: fixed-potential PEC objects, dielectric/magnetic materials, volume charges, <i>etc</i>. All the objects belonging to the same charge group have the same color and the same charge density.

To create a new charge category, right-click on the '''Volume Charges(Heat Sources)''' item in the navigation tree and select <b>Insert New Charge Source...</b> from the contextual menu. The New Charge Source dialog opens up with a default name CS_1 and a default purple color. In the section titled "Source Properties", you will see a default value of -1e-5C/m³ for '''Charge /Heat Density'''. This means a default negative charge. Replace this with a positive value of +1e-8 C/m³. Close Click the OK button and close the dialog and return to the project workspace (main window). The last object group created in the navigation tree remains as the "Active" group, and its name is displayed in bold letters, meaning that all the objects you draw will belong to this group.

[[EM.Cube]]’s computational modules usually generate two types of data: 2D and 3D. 2D data are graphed. 3D data are visualized in [[EM.Cube]]’s project workspace, and the plots are usually overlaid on the physical structure. The field sensor section of the navigation tree has a list of twelve amplitude and phase plots for all the six field components: E_x, E_y, E_z, and H_x, H_y, H_z. There are also two additional plots for the magnitude of total electric field and total magnetic field as well as the electric scalar potential and the magnitude of the magnetic vector potential. In an electrostatic simulation, the magnetic field is assumed to be zero. Therefore, you will only have electric field and electric potential plots. Moreover, both the field and potential are real-valued. The electric potential is plotted on a color-coded intensity plots that may involve both negative and positive values. Click on any of these plots to display them in the project workspace. You can use the standard view operations such as dynamic zoom, rotate view, pan view, <i>etc</i>. to better examine these plots.

Select the data files “Sensor_1_X_ETotal.DAT” and "Sensor_1_X_EPotential.DAT" by highlighting them in the data manager's list. Note that you can make multiple selections using your keyboard's {{key|Ctrl}} or {{key|Shift}} keys. Click the {{key|Plot}} button to open of the graphing utilitydialog. The A PyPlot graph window pops up that shows the the total E-field and the electric potential are plotted as functions of the coordinate X on two Cartesian graphs as shown in the figures below.  The graphs are interactive. As you move the mouse on the graph, you can read the value of the horizontal axis (X) and the corresponding value of the total electric field distribution along the X Y direction on the lower right corner of the status bar. The PyPlot window has also a number of controls that let you change the settings of your graph using your mouse. For example, using the Pan/Zoom button [[Image:Py_zoom_icon.png]], you can pan the graph with the left mouse button and zoom it in or out with the right mouse button. A combination of the two operations usually gives you an ideal scaling of your graph.

[[Image:Ferma L1 Fig18Fig19.png|thumb||left|480px|THE The 2D Cartesian graph of the total electric potential field along the X-axis.]]

[[Image:Ferma L1 Fig19Fig18.png|thumb||left|480px|THE The 2D Cartesian graph of the total electric field potential along the X-axis.]]

The 3D field plots are displayed as intensity plots by default. You can also shows them as vector plots made up of a collection of arrows whose orientation, color and length indicate both the direction and strength of the field. To do so, right-click on the name of "Sensor_1" in the navigation tree and select '''Properties''' from the contextual menu. In the field sensor dialog, choose '''Vector''' as the '''Plot Type'''. Also, set the values of '''Max Size''' to 0.5mm and '''Cone Length Ratio''' and '''Cone Radius Ratio''' to 0.9 5 as shown below. You can freeze any geometric objects to see other objects hidden behind, beneath or inside it. In that case, you will see a wireframe outline of the frozen object and you cannot select it. To freeze an object, right-click on its surface in the project workspace or right-click on its name in the navigation tree and select '''Freeze''' from the contextual menu. To unfreeze, repeat the same procedure. Freeze Sphere_1 and Sphere_2 objects. Now visualize the total electric field map as shown in the figure below.