On the basis of three-dimensional Monte-Carlo simultaneous of the hadronic component of extensive air showers the electromagnetic component of extensive air showers has been investigated theoretically using approximative electromagnetic cascade theory. Results include the relation between mean total electron number and primary energy as well as mean lateral distribution of electrons. Fluctuations of parameters of the structure function, central density and width of density distribution in sets of showers with given initial conditions are presented and found to be strong.