electricity.jpg (5852 bytes)

LIGHTENING EFFECTS AND SPARK ARRESTOR



EQUIPMENT
    redball.gif (326 bytes) Wimshurst Machine
    redball.gif (326 bytes) Horizontal Parallel Plates
    redball.gif (326 bytes) Small Spherical Object
    redball.gif (326 bytes) Small Pointed Object
    redball.gif (326 bytes) Shorting Device
    redball.gif (326 bytes) Insulated Rod



NARRATIVE
            Surfaces or objects with large radii of curvature build up more charge before discharging than surfaces or objects with small radii of curvature (e.g. a point).  Insert the spherical object between the discharged plates which are connected to the Wimshurst machine.  Adjust the gap between the sphere and the top plate to about 2 cm.  Crank the Wimshurst machine and the ball will discharge with periodic large sparks. Stop the machine and discharge it.  Place the pointed object with the spherical object between the plates.  (Notice that the spherical object is taller.)  Crank the Wimshurst machine.  A spark will not occur until the pointed object (lightening arrestor) is removed by pushing it out with an insulated rod.

            The Van de Graaff generator may be used instead of the Wimshurst machine and vice versa in these demonstrations.

Does not work well in high humidity.