如图所示,处在磁感应强度为B的匀强磁场中的单匝矩线圈abcd,以恒定的角速度ω绕

题型:选择题

问题:

如图所示,处在磁感应强度为B的匀强磁场中的单匝矩线圈abcd,以恒定的角速度ω绕ab边转动,磁场方向垂直于纸面向里,线圈所围面积为S,线圈导线的总电阻为R.t=0时刻线圈平面与纸面重合,且cd边正在离开纸面向外运动.则正确的是(  )

A.时刻t线圈中电流的瞬时值icosωt

B.线圈中电流的有效值I

C.线圈中电流的有效值I=

D.线圈消耗的电功率P

考点:正弦式交变电流交变电流的周期和频率
题型:选择题

阅读下列各小题,根据括号内的汉语提示,用句末括号内的英语单词完成句子

小题1:Many old houses _______ (拆除) to make way for the new road in the past few weeks. (tear)

小题2:The 26th Shenzhen summer Universiade was grandly opened on August 12th.___________ (最吸引我们的) was the door to the world formed by the 365 electronic giant LED screen. (appeal)

小题3:Not only ________________________ (她懂得法律) very well, she can also apply it in new ways. (know)

小题4:Those successful deaf dancers think that dancing is an activity ____________ (视觉更重要) than hearing. (matter)

小题5: _______________________ (确立了目标群体后),researchers find out as much as possible about thos in the target group, such as their likes and dislikes, and how the product would fit into their lives. (identify)

小题6:Everything ___________________________ (加以考虑), the environmental problem we are looking forward to seeing solved is worthy of our government’s attention. (consideration)

小题7:Tom insisted that the new release of the product planned for today ________ (延期) to next week because of the terrible financial situation at yesterday’s meeting. (postpone)

小题8: The boy _________________________ (如此迷恋于) the cyber games that he would spend hours sitting in front of the computer. (fascinated)

小题9:I _____________________________ (多亏了我的父母) that I went through the hard time after I lost my job. Everything couldn’t have been going so smoothly without them. (owe)

小题10: _________________________ (作为回答) your inquiries, we regret to tell you that we can not help you in this matter. (response)

题型:选择题

利用电磁继电器可以用低电压、弱电流控制________的工作电路,还可以实现________和________。

题型:选择题

某厂产品的合格率为90%,今抽查其中的100件产品,发现只有5件不合格,因此:

A.以前的合格率计算错误

B.如果再抽查一次,可能又是另一种结果

C.该厂产品的合格率是95%

D.如果抽查200件产品,肯定会有10件不合格产品

题型:选择题

浮充电运行的铅酸蓄电池单只电池的电压应保持在()。

A、2.00±0.05V

B、2.05±0.05V

C、2.10±0.05V

D、2.15±0.05V

题型:选择题

人们用能量金字塔来说明生态系统中的()

A.能量与营养级的关系

B.能量与个体大小的关系

C.能量与个体数量的关系

D.能量与生物代谢类型的关系

更多题库