Illustrations that I have added to Wikimedia Commons and inserted in some articles:
Illustration of the electric field surrounding a positive (red) and a negative (green) charge (click for larger image). I inserted this illustration in the Electric field article.
Illustration of the electric field surrounding two equal charges (click for larger image).
Illustration of the electric field surrounding one positive charge (click for larger image). I'm not quite satisfied with this one, but I don't see any article where it would be obvious to use, so I won't improve it just now.
What are portals? "Doorways to knowledge." Wikipedia's coverage of subjects can be extensive (mathematics, for example, is covered by tens of thousands of articles on Wikipedia). Portals are an alternative entry to a subject (besides its main article), and to that subject's coverage in the encyclopedia, in a way similar to how the Main Page provides sample fare from Wikipedia as a whole.
Portals may include features such as Selected article sections, Selected image, news, points of interest (Did you know?, Anniversaries), and links to related Wikimedia. Portals are more diverse than the Main page, and may include features such as panoramic banners, slide shows, category trees, topics lists, and whatever else portal designers can come up with.
A secondary purpose of portals is to provide bridges between reading and editing, and between the encyclopedia and the Wikipedia community. They may provide links to the related WikiProjects, Wikipedia's Reference desk, and so on. Portals are a hybrid between encyclopedia pages and project pages, and occupy their own special namespace, the Portal namespace. Therefore, all portal titles are preceded by the prefix "Portal:"
The list of all completed portals is Portal:Contents/Portals. A list of all portals, including those under construction, can be found at Category:All portals. The Portals WikiProject is dedicated to collaboratively building and maintaining portals, and further expanding on the Portal concept, such as with automated features, and is always looking for new participants.
Illustration of the electric field surrounding a positive (red) and a negative (green) charge (click for larger image). I inserted this illustration in the Electric field article.
Illustration of the electric field surrounding two equal charges (click for larger image).
Illustration of the electric field surrounding one positive charge (click for larger image). I'm not quite satisfied with this one, but I don't see any article where it would be obvious to use, so I won't improve it just now.
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