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This java applet demonstrates standing electromagnetic waves in a 3-d rectangular waveguide. To use the applet, double-click on one of the grid squares to select a mode. The TE modes are on top and the TM modes are on the bottom. Use the menu items to select the electric or magnetic field, and the way the field is displayed.

Full Directions.

Zip archive of this applet.

Cavity resonator applet.

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The source.