题目

如图所示,矩形线圈abcd与可变电容器C、理想电流表A组成闭合电路.线圈在有界匀强磁场中绕垂直于磁场的bc边匀速转动,转动的角速度ω=100π rad/s.线圈的匝数N=100匝,边长ab=0.2 m、ad=0.4 m,电阻不计.磁场只分布在bc边的左侧,磁感应强度大小B= T.电容器放电时间不计.下列说法正确的是( )A.该线圈产生的交流电动势峰值为50 V B.该线圈产生的交流电动势有效值为50 V C.电容器的耐压值至少为50 V D.电容器的电容C变大时,电流表的指针会左右往复摆动根据句意、汉语提示或首字母和英文释义写出单词的正确形式。 1. —I don't like this CD-ROM.         —Me_________(也). 2. Have you_________(回复) to his letter? 3. China Daily is a_________(窗口)for foreigners to know about China. 4. It is said that the Opening Ceremony of the Bei­jing   2008   Olympic   Games   will   be   covered_____(实况转播). 5. Look!   Some   birds   are   ___________ (飞 ) in the sky. 6. National Day is on O_______(the tenth month of the year) 1st. 7. Do you know how long Yancheng Railway Sta­tion has been in s_______(use)? 8. People use mobile phones to sent short text m_______(pieces of information)to each other. 9. Could you please give me some v_______(very useful and helpful) advice on how to keep fit? 10. I've heard of Jackie Chan for years. Since I was a child,a_______(in fact).