【单选题】Section B Directions: In this section, you will hear two passages. At the end of each passage, you will hear three or four questions. Both the passage and the questions will be spoken only once. After...
【简答题】Section b Directions: in this section, you will hear two passages. at the end of each passage, you will hear Iree or four questions. both the passage and the questions will be spoken only once After y...
【简答题】如图所示,交流发电机的矩形线圈 abcd 中, ab = cd = 50 cm , bc = ad = 30 cm ,匝数 n = 100 ,线圈电阻 r = 0.2 Ω ,外电阻 R = 4.8 Ω 。线圈在磁感应强度 B = 0.05 T 的匀强磁场中绕垂直于磁场的转轴 OO ′ 匀速转动,角速度 ω = 100 π rad/s 。 (1) 求产生感应电动势的最大值; (2) 若从图示位置开始...