用有限差分法计算静电场问题,两平行的无限大极板接地，在它们中间平行放置一半极大的极板，该极板接电位为V，求解该静电场的分布.-Electrostatic field problems using finite difference method, the two infinite parallel plates grounded, among them, placed parallel to the great half of the plate, the plate then potential V, for solving the electrostatic field distribution.