The toy is made up of a table with two rows of plates of different metals. The plates of a given rows are linked directly to some wires whose extremity are linked to the voltmeter.

The circuit "metal - body - other metal" is an example of chemical cell, whose working principle is the Volta's electro-chemical serie (Al, Zn, Sn, Cd, Pb, Bi, Hg, Fe, Cu, Ag, Pt, Pd).

The more the metals are distant among each other in the Volta's serie, the more the value of the electro-magnetic strength generated is high.

A detailed explanation of Volta's electrochemical series is related to microscopic properties of matter, and more precisely to the electronic properties called a work function. Every substance has its characteristic energy needed to emit electrons. If we consider two different metals connected, such a connection creates a difference in the electric potential, due to these different work functions.

However, such a contact itself is insufficient to produce useful electricity. If we try to close the electric circuit (with the same or another metal) an opposite sign and equal amplitude difference of the potential will be created on the second junction and no useful current will flow. To create a useful difference of potentials one of the two contacts has to be at a different temperature. In this way a thermoelectric generation of current occurs (Seebeck's effect).

Another way of generating useful amounts of electricity is by putting the second contact in other medium, like a liquid (so-called electrolyte which is able to dissolve this metal). In the IQ meter, the second contact, closing the circuit, is made of your body.

Our IQ meterconsists of Zn and Cu plates (like in the traditional Volta's pile). Under favourable circumstances (wet hands) a potential of about 1 V should be observed.