A slab of copper thickness b is thrust into a parallel plate capacitor as shown in the figure. It is exactly halfway bet- ween the plates. If a charge q is maintained on the plates, how much work is done on the slab as it is inserted. ○ | 截面A | ↙ ---------------------- -- ↑ ↑|￣￣￣￣￣￣￣￣￣￣| ︱ b ︳ Copper | ︱D ↓|╴╴╴╴╴╴╴╴╴╴| ︱ ↓ ---------------------- -- | | ○ 不清处为什麽插入铜板须要作功 如果说 今天不插入铜板 那麽我们把平行板原距离D拉到D+b 那麽电位能居然会跟插入一片铜板一样 把平行板拉开外力作功=位能增加 但是今天插入一个铜板 插入後才有感应电荷不是吗？ 两平行板并没有被拉开 而且~~铜板还占据两板间的空间 谢谢!! ※ 编辑: Qmmm 来自: 58.115.142.156 (04/09 06:31)