问题
选择题
要使LC振荡电路的周期变大，可用的方法是( )
A．增大电容器初始带电荷量
B．线圈中插铁芯
C．增大电容器两极板正对面积
D．增大平行板电容器两极板间距离
答案
BC
由周期公式T=2π
可知，T与q无关；插入铁芯，L变大，T变大；由C=
知，S增大，T增大，而d增大，T减小。
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要使LC振荡电路的周期变大，可用的方法是( )
A．增大电容器初始带电荷量
B．线圈中插铁芯
C．增大电容器两极板正对面积
D．增大平行板电容器两极板间距离
BC
由周期公式T=2π可知，T与q无关；插入铁芯，L变大，T变大；由C=知，S增大，T增大，而d增大，T减小。
| 阅读理解。 | ||||||||||||||||||
| Lifelong Learning (终身学习) In the past, when students graduated (毕业) from college and got jobs, only some of them went on with their study. But today, lifelong learning is becoming more and more common (常见的). Lucy, who is forty, teaches physics at a college in Boston. "Next term, I'll teach some of classes by using the Internet. This is the way of teaching that I've never used before," says Lucy. "These days, I am taking a class to learn how to teach in this way, If not, I will lose my job." At the same time, Lucy's seventy-year-old parents, who live in New York, are taking an art history class online. "We love this subject," says her father, "and we learn it to enjoy ourselves. You see we can study with people all over the world. What fun it is to learn like this!" | ||||||||||||||||||
根据上文，完成下面的表格，数词要用英语写出。
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