您所在的当前位置：高中物理试题 >

通电导线在磁场中受到的力

> 很多相同的绝缘铜圆环沿竖直方向叠放，形成一很长的竖直圆筒。一条形磁铁沿圆筒的中心轴竖直放置，其下端与圆筒上端开口平齐。让条形磁铁从静止开始下落。条形磁铁在圆筒中的运动速率（） A．均匀增大 B．先增大，后减小 C．逐渐增大，趋于不变 D．先增大，再减小，最后不变

问题：

发布时间：2024-09-11

很多相同的绝缘铜圆环沿竖直方向叠放，形成一很长的竖直圆筒。一条形磁铁沿圆筒的中心轴竖直放置，其下端与圆筒上端开口平齐。让条形磁铁从静止开始下落。条形磁铁在圆筒中的运动速率（）

A．均匀增大 B．先增大，后减小 C．逐渐增大，趋于不变 D．先增大，再减小，最后不变

参考答案：

提问用户：qr***62n

可能感兴趣的题目：

1 读我国某区域图（图19），回答问题。（13分）（1）我国两大重要的能源跨区域调配工程和都经过该地区，以上工程对该地区的积极影响有。（5分）（2）该地区风能资源较为丰富，尤其在季；此外该地区的太阳能资源也较充足，原因是。（2分）（3）A、B两地区突出的生态环境问题分虽是A ；B 。（2分）（4）据图分析甘肃在黄河沿岸]二业迅速发展的有利自然条件有，工业发展给当地环境带来的负面影响主要有。（4分）
2 People who don"t smoke have less ______________ of suffering from lung disease than those who smoke. [ ] A. potential B. cause C. hope D. problem
3 It"s the end of class. When the bell rings, students of Luohu Foreign Languages School in Shenzhen quickly take out their cell phones. They want to log on to their micro blogs（微博） to check the interesting things that have happened in the last hour. Since last year, the trend of micro blogging has swept the country. Recent surveys shows that most students in middle schools have a micro blog and some even update their blogs over five times per day. "We learn many fresh and interesting things on micro blogs and they have become popular topics in class," said Andy Liang, 14. "If you do not know about them, you are out." It is also a great place for students to let out stress. "My parents always ask me to study hard, and encourage me before exams, but it really adds pressure," said Simon Zhang, 15. "When I share these feelings on my micro blog, I get many replies from friends in the same situation, which makes me feel better." But parents are worried that micro blogging could be a waste of time. Some misleading messages may even cause danger to kids, they said. Mr. Shen, a professor at the China Education Association, suggests parents not worry too much as long as kids are not crazy about micro blogging. Maybe it can become a window for parents to understand their children. "If parents can read their children"s micro blogs, they"ll know their thoughts, thus leading to better communication and solutions to problems," he said. He also gives some tips for kids. -Don"t micro blog for more than one hour a day. -Never micro blog in class. -Try to talk face to face with people from time to time. -Be critical(批判性的). Don"t trust all the messages on a micro blog. 小题1:Students log on to their micro blogs to . A．check the things B．write articles C．listen to music D．call their parents 小题2:Micro blog made Simon when he shared his feelings and got replies on his micro blog. A．feel sad B．let out stress C．add pressure D．make friends 小题3:We can know from Mr. Shen that micro blogging can . A．make kids crazy while logging on to it B．bring a lot of misleading messages C．become a window to understand young kids D．lead to worse communication 小题4:Don"t micro blog for a day . A more than one hour B. less than one hour C. one hour D. more than two hours 小题5:Which is Wrong ? A．Never micro blog in class. B．They"ll know their thoughts through micro blog. C．Trust all the messages on a micro blog. D．Be critical(批判性的)
4 浓 H 2SO 4与下列物质作用时，只体现酸性的是（） A．氧化镁 B．碳粉 C．蔗糖 D．铜
5 据媒体报道，俄罗斯计划修建连接美国和俄罗斯的海底隧道，该隧道将是世界上投资最大、最长的海底隧道．该海底隧道最有可能位于 A.白令海峡 B.英吉利海峡 C.霍尔木兹海峡 D.土耳其海峡
6 如图所示，矩形区域MNPQ内有水平向右的匀强电场，虚线框外为真空区域；半径为R、内壁光滑、内径很小的绝缘半圆管ADB固定在竖直平面内，直径AB垂直于水平虚线MN，圆心O恰在MN的中点，半圆管的一半处于电场中．一质量为m，可视为质点的带正电电荷量为q的小球从半圆管的A点由静止开始滑入管内，小球从B点穿出后，能够通过B点正下方的C点．重力加速度为g，小球在C点处的加速度大小为5g/3．求：（1）匀强电场场强E；（2）小球在B点时，半圆轨道对它作用力的大小；（3）要使小球能够到达B点正下方C点，虚线框MNPQ的高度和宽度满足什么条件；（4）小球从B点计时运动到C点过程中，经多长时间小球的动能最小．
7 在蒸馏实验中，下列叙述不正确的是 A．在蒸馏烧瓶中加入约1/3体积的自来水，并放入几粒碎瓷片 B．蒸馏结束时，先停止通冷却水，再熄灭酒精灯 C．冷水从冷凝管的下口入，上口出 D．收集冷凝水时，应弃去开始蒸馏出的部分
8 Nothing can stop us doing that, ? A．can we B．can’t we C．can’t it D．can it
9 The committee decided to the best film the first prize. A．reward B．benefit C．pay D．award
10 工业地域的规划建设应遵循的原则是 [ ] A、以新兴工业部门为主 B、布置在城市的远郊 C、与当地的优势条件和发展潜力相结合 D、布置在主导风的上风地带