If any sensible current flows through this insulator the galvanometer will show a deflection.
Theoretically this requires an infinite plate; or a perfect heat insulator, so that the lateral flow can be prevented or rendered negligible.
Of the ends of the insulator and the current flowing through it, that is, by its insulation resistance.
First as regards the transmitting part, one essential element is the antenna, aerial, or air wire, which may take a variety of forms. It may consist of a single plain or stranded copper wire upheld at the top by an insulator from a mast, chimney or building.
The electroscope is provided with a charging rod C. In a dry atmosphere sulphur or amber is an early perfect insulator, and hence if the air in the interior of the box is kept dry by calcium chloride, the electroscope will hold its charge for a long time.