题　原子中的电子绕原子核的运动可等效为环行电流 .设氢原子的电子以速率 v在半径为 r的圆周轨道上绕核运动 ,电子的电荷量为 e,等效电流有多大 ?这道题可以说是作为经典好题出现在各种资料中 ,甚至被收入了教材 ,如人民教育出版社《物理》第二册 (试验修订本·必修加选修 )第 The movement of electrons in the problem atom around the nucleus can be equivalent to a ring current. Let the electrons of the hydrogen atom move around the nucleus at a rate v in a circular orbit of radius r, the charge of the electron is e, and how large is the equivalent current? The topic can be said to appear as a classic good question in various materials and even be included in the teaching materials, such as the second edition of the “Physics” of the People’s Education Publishing House (Test Revision, Compulsory and Optional).