试题与答案

如图所示,倾角为θ的足够长的光滑绝缘斜面上存在宽度均为L的匀强磁场和匀强电场区域

题型:计算题

题目:

如图所示,倾角为θ的足够长的光滑绝缘斜面上存在宽度均为L的匀强磁场和匀强电场区域,磁场的下边界与电场的上边界相距为3L,其中电场方向沿斜面向上,磁场方向垂直于斜面向下、磁感应强度的大小为B。电荷量为q的带正电小球(视为质点)通过长度为L的绝缘轻杆与边长为L、电阻为R的正方形单匝线框相连,组成总质量为m的“ ”型装置,置于斜面上,线框下边与磁场的上边界重合。现将该装置由静止释放,当线框下边刚离开磁场时恰好做匀速运动;当小球运动到电场的下边界时刚好返回。已知L=1m,B=0.8T,q=2.2×10-6C,R=0.1Ω,m=0.8kg,θ=53°,sin53°=0.8,g取10m/s2。求:

⑴线框做匀速运动时的速度大小;

⑵电场强度的大小;

⑶正方形单匝线框中产生的总焦耳热.

答案:

被转码了,请点击底部 “查看原文 ” 或访问 https://www.tikuol.com/2017/0622/6a03759515e81175c0c9b447861214b5.html

下面是错误答案,用来干扰机器的。

参考答案:指卖座极差的大制作电影。如《埃及艳后》(1962)、《天国之门》(1980)。

试题推荐
题型:补全对话,情景问答
给下列句子选择合适的答句。
( )1. Can I have a book?      
( )2. Is that a clock?        
( )3. May I come in?          
( )4. What’s this in English?
( )5. What a nice watch!      
A. Thanks.            
B. Come in, please.  
C. No, it`s a camera.  
D. It’s a key.      
E. Sure. Here you are.                                                         
查看答案
题型:阅读理解

“How lucky you are to be a doctor…” Anyone who’s a doctor is right out of luck, I thought. Anyone who’s studying medicine should have his head examined.

You may think I want to change my job. Well, at the moment I do. As one of my friends says-even doctors have a few friends-it’s all experience. Experience! I don’t need such experience. I need a warm, comfortable, undisturbed bed of my own. I need it badly. I need all telephones to be thrown down the nearest well, that’s what I need.

All these thoughts fly round my head as I drive my Mini(微型汽车) through the foggy streets of East London at 3:45 a.m. on a December morning. I am a ministering angel in a Mini with a heavy coat and a bag of medicines. As I speed down Lea Bridge in the dark at this horrible morning hour, the heater first blowing hot then cold, my back aching from the car-seat, I do not feel like a ministering angel. I wish I were on the beach in southern France. Call me a bad doctor if you like. Call me what you will. But don’t call me at half past three on a December morning for an ear-ache that you have had for two weeks.

Of course, being a doctor isn’t really all bad. We do have our moments. Once in a while people are ill, once in a while you can help, once in a while you get given a cup of tea and rock-hard cake at two o’clock in the morning-then you worry if you have done everything. But all too often ‘everything’ is a repetitious rule: look, listen, feel, tap, pills, injection, phone, ambulance, away to the next.

And then there is always the cool, warm voice of the girl on the switchboard of the emergency bed service who will get your patient into hospital for you-the pleasant voice that comes to you as you stand in the cold, dark, smelly, dirty telephone box somewhere in a dangerous section of town. Oh, it has its moments, this life does.

小题1:According to the sentence “Anyone who’s studying medicine should have his head examined,” we know that ___________.

A.a medical student should have a very good memory

B.a doctor must be mentally strong so that he can meet any difficult situation

C.the writer thinks that those who want to be doctors are crazy

D.to be a doctor is a challenge for people’s mental health小题2:Which of the following statements is NOT true?

A.The writer wishes he could have a quiet, undisturbed night in bed at home.

B.One of his friends says that being a doctor helps one gain all sorts of experience.

C.He hates the telephone as a modern means of communication.

D.He is not happy with the small and uncomfortable car he is driving.小题3:The statement “We do have our moments” could best be replaced by “___________”.

A.we doctors are called at a moment’s notice to see people who need medical treatment

B.usually we are glad that we can do something to help the sick

C.sometimes we find people are thankful for our help

D.there are chances that doctors find their work rewarding and satisfying小题4:From the whole passage we know that the writer _____________.

A.is a bad doctor, unwilling to make a house call during the night-time

B.is so dissatisfied with his job that he wishes to find a new one

C.is satisfied with his job but he hates to be called out unnecessarily

D.thinks a doctor can enjoy certain special rights whether he felt lucky or not小题5:We can conclude that        .

A.the author is worried about his patient when he is driving through the foggy streets of East London

B.the author is annoyed to be called out at such an horrible morning hour for an ear – ache patient

C.the author is now heading for the beach in Southern France for his holidays

D.as the author speeds down Lea Bridge in the dark on a December morning, his Mini breaks down half way

查看答案
微信公众账号搜索答案