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 proportional to v_∞B_∞² sin² (θ_∞ ‐ ϕ_∞), where v_∞ and B_∞ are the solar wind speed and magnetic field and θ_∞ ‐ ϕ_∞ 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(θ_∞/2) energy flux dependence of Akasofu's ε‐index.