you will see the two foil leaves of the electroscope spring apart. They are reacting to the record’s static electric charge.

    Now bring the alpha radiation source close to the electroscope ball under the record, with the source opening pointing at the ball. As the alpha particles discharge the static electricity (by producing ions in the surrounding air), the foil leaves will drop to their original position.

    If you rotate the large glass slightly, you will shift a still charged part of the record’s surface over the electroscope. The leaves will fly apart again.

    Repeat the experiment several times, holding the alpha source at different distances each time. You will observe that the farther away the source is from the record, the longer it takes to discharge the static electricity over the foil ball.

    NOTE:  Before  dismantling  your equipment,  read Experiment 7.