You can switch on (off) the current by using the upper button ("On / Off"). The other two buttons ("Reverse Current" and "Turn Magnet") make it possible to change the direction of the current respectively of the magnetic field. If the corresponding checkboxes are selected, the applet indicates the technical current direction (blue arrows), the magnetic field lines (violet) and the Lorentz force (black arrow). Source code available. Foreign language versions available.