It is assumed there are uniform magnetic field in the simulation region except white background area (there is no magnetic field).
An electron enter magnetic field is not trapped in the magnetic field. It will come out the region eventually.

You can change charge/ mass /magnetic field and the width of the white region with sliders. Enjoy it!

VIEW or DOWNLOAD ejs xml source
then click to translate strings for selected locale.

Press the Alt key and the left mouse button to drag the applet off the browser and onto the desktop.