一、原题展现均匀带电球壳在球外空间产生的电场等效于电荷集中于球心处的点电荷产生的电场。如图1甲所示在半球面AB上均匀分布正电荷,总电荷量为q,球面半径为R,CD为通过半球顶点与球心O的轴线,在轴线上有M、N两点,OM=ON=2R,已知M点的电场强度为E,则N点的场强为() First, the original show uniform charged spherical shells in the outer space generated by the electric field is equivalent to the electric charge at the ball center of the electric charge generated by the electric field. As shown in Fig. 1 A, the positive charge is uniformly distributed on the hemispherical surface AB, the total charge is q, the radius of the spherical surface is R, CD is the axis passing through the apex of the hemisphere and the center O of the sphere, there are two points M and N on the axis, = ON = 2R, it is known that the electric field strength at point M is E, then the field strength at point N is ()