题干

甲、乙两位同学从一些废旧的电动玩具上取材组装了如图所示的装置.

(1)若在a、b两接线柱之间接一电池,会出现什么现象?

(2)若先在a、b两接线柱之间接上小灯泡,然后转动线圈,会出现什么情况?

(3)有上述两种情况可见,此装置为电动机还是发电机,为什么?

上一题 下一题 0.0难度 选择题 更新时间:2017-09-29 06:01:49

答案(点此获取答案解析)

答:

分析图片可以看出,图中有线圈和磁极;

(1)若在a、b两接线柱之间接一电池,即给线圈通电,根据通电导体在磁场中受磁场力作用会运动,所以线圈可以转动起来;

(2)线圈在磁场中转动,线圈要切割磁感线,这时线圈中会产生感应电流,若在a、b两接线柱之间接上小灯泡,小灯泡会发光;

(3)在(1)中电池给线圈通电,利用通电导线在磁场中受力的作用的原理制成的是电动机,故此时是电动机;

在(2)中通过线圈在磁场中转动而产生电流,即是利用电磁感应现象来

同类题5

阅读理解

    Filmmaker Jennifer Nelson had to pay $1,500 to have “Happy Birthday to You” sung in the movie she's making. The money went to Warner Music Group, a company that claims to own the copyright on the song. A copyright is the legal right to use or sell a creative product such as a song, a TV show, a book, or a work of art. Warner has claimed the copyright for “Happy Birthday to You” since 1988.

    “I never thought the song was owned by anyone,” Nelson said in an e-mail to The New York Times. “I thought it belonged to everyone.”

    Nelson's movie is a documentary — a film that uses pictures and/or interviews with people to create a factual report of real-life events — and is actually about the history of the “Happy Birthday” song itself.

    Two sisters named Mildred and Patty Hill wrote a song called “Good Morning to All” in 1893. Over a short period of time, people began to sing the words “happy birthday to you” in place of the original lyrics to the tune of the Hill sisters' song.

    A number of history experts say that there is no record of who actually wrote the “Happy Birthday to You” lyrics. Historians also say there is no way to know when the general public began singing the “Happy Birthday” song, but they believe it was being sung by the public long before it was printed and owned by a company.

    Nelson's lawyers say this piece of music's history proves that “Happy Birthday to You” belongs to everyone in the general public. That would mean Warner Music Group has no right to charge anyone a fee to sing the song in any setting.

    Experts estimate that Warner/ Chappell, the publishing division of the Warner Music Group, has made about $2 million a year from licensing fees for “Happy Birthday to You.”

    Nelson's lawyers are asking a court in New York City to order Warner/Chappell to return fees they have collected over the past four years for use of the “Happy Birthday” song.