Electric Two-Shell Analysis Notes

The Electric Two Shell Analysis Interactive is an adjustable-size file that displays nicely on tablets such as the iPad, on Chromebooks, and on laptops and desktops. The size of the Interactive can be scaled to fit the device that it is displayed on. While it works on smartphones, the screen size is a bit prohibitive given the density of information that is contained in the Simulator; we recommend a larger screen. The compatibility with iPads, other tablets, and Chromebooks make it a perfect tool for use in a 1:1 classroom.

This simulation allows a user to explore the electric field and electric potential value inside, between, and outside the surfaces of two charged, concentric spherical shells. The interface includes a diagram of the two shells (or at least the right side of those shells). Electric field lines between the two shells and in the space outside of the two shells is represented by electric field vectors. The bottom half of the Interactive displays a plot of the electric field intensity (in yellow) and the electric potential (in orange) as a function of location. The surface of the shells are color coded with red representing a positive charge and blue representing a negative charge. The intensity of the red or of the blue colors are representative of the density of charge on those surfaces.

There are a variety of controls that allow one to investigate the effect of various parameters upon the E and V values. First, the inner and outer radius of each shell can be altered by dragging one of the four red dots shown on the inner and outer surfaces of the shells. As changes are made, a numerical value for the position of the surface relative to the center of the shell is updated in real time. These controls allow one to investigate any possible effects of the shell width upon the values of the electric field and the electric potential and upon the electric charge density on each shell surface. Users should note the presense of dashed, vertical lines inside of the plotted area to indicate the radius values of the inner and outer surface of these two shells. These dashed lines will help users better recognize how E and V are changing (or not changing) inside and outside of the shells.

Second, the total charge on each shell can be varied using the two sliders in the upper right section of the simulation. A positive or a negative value can be selected for each shell. The effects of these changes on the inner and outer shell surfaces are immediately displayed by a numerical value for charge (stated in Coulombs or C). Finally, the material the shell is composed can be toggled between an insulator and a conductor.