题干

如图所示,边长为100cm的正方形闭合线圈置于磁场中,线圈ab、cd两边中点连线OO′的左右两侧分别存在方向相同,磁感应强度大小各为B1=0.6T,B2=0.40T 的匀强磁场,若从上往下看,线圈逆时针转过37°角时,穿过线圈的磁通量改变了多少?

上一题 下一题 0.0难度 选择题 更新时间:2019-03-23 10:02:18

答案(点此获取答案解析)

解:初始位置时,线圈与磁场垂直,穿过线圈的磁通量Φ1=(B1+B2)S;

线圈逆时针转过37°角时,磁通量为Φ2=(B1+B2)S•cos37°,

则△Φ=Φ2﹣Φ1=(B1+B2)S•cos37°﹣(B1+B2)S;

同类题1

根据短文理解,选择正确答案。

    On the first day of school our teacher introduced himself and challenged us to get to know someone we didn't already know. I stood up to look around when a gentle hand touched my shoulder.

    I turned around to find a little old lady with a warm smile. She said, “Hi, handsome. My name is Rose. I'm eighty-seven years old.”

    “Why are you in university at such a YOUNG age?” I asked. She replied, “I'm here to meet a rich husband, get married, have a couple of kids, and then retire and travel.”

    I knew she was joking. I was curious what might have encouraged her to be taking on this challenge at her age.

    “I always dreamed of having a university education and now I'm getting one!” she told me. We became friends. Every day we would talk nonstop after class. I always enjoyed listening to this “time machine” as she shared her wisdom and experience with me. And Rose easily made friends wherever she went.

    At the end of the term we invited Rose to make a little speech. She cleared her throat(喉咙) and began, “We do not stop playing because we are old; we grow old because we stop playing. I've learned a few secrets to staying young, being happy, and achieving success. You have to laugh and find humor every day. You've got to have a dream. When you lose your dreams, you die.”

    “There is a huge difference between growing older and growing up. Anybody can grow older. That doesn't take any talent or ability. The idea is to grow up by always finding the opportunity(机会) in change...”