题目

Hey there,So you’re about to spend four years of your life and tens of thousands of dollars of your parents’ money, and all you really know about college is that all of your friends are going. Do you ever stop to wonder why you’re going?Relax. You’re making the right decision. First of all, you’ll discover what interests you by taking courses in many subjects. For example, it’s hard to decide if you want to be a painter if you’ve never painted any pictures; once you’re in a drawing-room on campus, you’ll know one way or the other. College is also a lot of fun—after you grad如图所示，水平放置的平行板电容器，原来AB两板不带电，B极板接地，它的极板长L= 0.1m，两板间距离d = 0.4 cm，现有一微粒质量m=2.0×10-6kg，带电量q=+1.0×10-8C，以一定初速度从两板中央平行于极板射入，由于重力作用微粒恰好能落到A板上中点O处，取g=10m/s2．试求： 1.带电粒子入射初速度的大小； 2.现使电容器带上电荷，使带电微粒能从平行板电容器的右侧射出，则带电后A板的电势为多少？