Volta eventually created an apparatus able to detect electrical charges which were too small for his electroscope to detect. This new device was called the condensing electroscope, or Condenser , represented in The Wheel of Fortune . It consisted of two discs separated by a thin insulation. If an electrical charge is applied to one disk while the other is grounded, one plate will move away from the other. Volta s primary contribution may be the proving of contact tension , represented by Trump 11, Strength .
Contact tension is the creation of electricity when two different metals are brought into contact.
This principle, which gives a battery its energy, could certainly be represented by traditional Strength images as well. The electrometer is depicted at the lower left of The Hanged Man card. These leaves will move away from each other when an electrically charged body is brought near to the upper brass sphere. This shows that the charged body is inducing a distribution of electrical charges. If the sphere is grounded, then disconnected, and then the charged body moved away from it, the gold leaves will remain separated by a force of repulsion.