题目两个同心薄金属球壳,半径分别为R_1和R_2(R_1A. U_2B. U_1+U_2C. (U_1+U_2)/2D. U_1两个同心薄金属球壳,半径分别为R_1和R_2(R_1A. U_2B. U_1+U_2C. (U_1+U_2)/2D. U_1题目解答答案A. U_2