What is the distance from O2 to Fz if the distance from O1 to Fz is 8 cm?

The distance from O2 to Fz can be determined based on the standardized positioning of the EEG electrode sites on the scalp. In the 10-20 system of electrode placement, O1 and O2 are located symmetrically on either side of the midline, with O1 being left of the midline and O2 being right of the midline.

Given that the distance from O1 to Fz is 8 cm, the distance from O2 to Fz will be the same since O1 and O2 are symmetrically positioned relative to the midline. However, Fz is not directly across from O2 but rather at a distance proportional to the arrangement of the electrodes.

In this context, the distance from O1 to Fz is used as a reference. The distance between Fz and O2 can be calculated as half the total distance between O1 and O2, reflecting the common practice of using O1’s known distance from Fz as a baseline measurement. Since O1 and O2 are placed symmetrically and the given measurement is from O1 to Fz, the distance from O2 to Fz can be calculated simply.

Thus, considering that O1 to Fz is