Based on the formation of a stagnation line at the magnetopause the electromagnetic energy transport from the solar wind into the dayside magnetosphere is analyzed. The resulting energy flux is analyzed. The resulting energy flux is proportional to v∞B∞sin2 (&thgr;∞-ϕ∞), where v∞ and B∞ are the solar wind speed and magnetic field and &thgr;∞-ϕs∞ is the angle between the IMF and the stagnation line projected into the interplanetary space. A stagnation line parallel to the separator gives approximately the sin4(&thgr;∞/2) energy flux dependence of Akasofu's &egr;-index.