《选修3-1》3.2磁感应强度(一课一练)

3.2 磁感应强度

1．磁场中某点磁感强度的方向是

A ．正电荷在该点的受力方向

B ．运动电荷在该点的受力方向

C ．静止小磁针N 极在该点的受力方向

D ．一小段通电直导线在该点的受力方向

2．关于磁感强度，正确的说法是：

A ．根据定义式IL

F B ，磁场中某点的磁感强度B 与F 成正比，与IL 成反比； B ．磁感强度B 是矢量，方向与F 的方向相同；

C ．B 是矢量，方向与通过该点的磁感线的切线方向相同；

D ．在确定的磁场中，同一点的B 是确定的，不同点的B 可能不同

3．磁感应强度的单位是特斯拉，用国际单位制中的基本单位可表示为

A ．N/A ·m

B ．kg/A ·s 2

C ．kg ·m 2/s 2

D ．kg ·m 2/A ·s 2

4．在磁感应强度的定义式B=IL

F 中，有关各物理量间的关系，下列说法中正确的是 A ．B 由F 、I 和L 决定 B ．F 由B 、I 和L 决定

C ．I 由B 、F 和L 决定

D ．L 由B 、F 和I 决定

5．有一小段通电导线，长为1㎝，电流强度为5A ，把它置入某磁场中某点，受到的磁场力为0.1N ，

该点的磁感应强度B 一定是 A ．B=2T B ．

B ≤2T

C ．B ≥2T

D ．以上情况都有可能

6．在匀强磁场中某处P 放一个长度为L=20㎝，通电电流I=0.5A 的直导线，测得它受到的最大磁

场力F=1.0N ，其方向竖直向上，现将该通电导线从磁场中撤走，则P 处的磁感应强度

A ．零

B ．10T ，方向肯定不沿竖直向上

C ．0.1T ，方向竖直向上

D ．10T ，方向竖直向上

7．如图3-２-1所示，有一根直导线上通以恒定电流I ，方向垂直指向纸内，且

和匀强磁场B 垂直，则在图中圆周上，磁感应强度数值最大的点是（ ）

A ．a 点

B ．b 点

C ．c 点

D ．d 点 图3-2-1

《选修3—1》

一课一练

8．一根通电导线垂直放在大小和方向都相同的磁场中。下列做法中，可以使磁场对导线的作用力减小为原来的一半的是

A ．电流增大为原来的两倍，导线在磁场中的部分的长度减小为原来的一半

B ．电流和磁感应强度都减小为原来的一半，导线在磁场中的部分的长度增大为原来的两倍

C ．导线在磁场中的部分的长度增大为原来的两倍，磁感应强度减小为原来的一半

D ．电流和导线在磁场中的部分的长度都减小为原来的一半，磁感应强度增大为原来的四倍

9．两根长直的通电导线互相平行，电流方向相同，它们的截面处于等腰直角三

角形ABC 的A 和B 处，如图3-2-2所示，两通电导线在C 处产生的磁感应

强度的值都是B 0，则C 处总磁感应强度是

A ．2

B 0 B ．0

C ．B 0

D ．2B 0

10．欧姆在探索通过导体的电流和电压、电阻关系时，因无电源和电流表，他利用金属在冷水和热水中产生电动势代替电源，用小磁针的偏转检测电源，具体做法是：在地磁场作用下处于水平静止的小磁针上方，平行于小磁针水平放置一直导线，当该导线中通有电流时，小磁针会发生偏转；当通过该导线电流为I 1时，小磁针偏转了30o，问当他发现小磁针偏转了60o，通过该直导线的电流为I 2（直导线在某点产生的磁场与通过直导线的电流成正比）

A ．I 2=2 I 1

B ．I 2=3I 1

C ．I 2=4I 1

D ．无法确定

11．一东西方向水平放置的直导线，加上一个竖直向下的匀强磁场，若直导线中电流方向为从东向西，那么，它所受安培力的方向为

A ．向上

B ．向下

C ．向南

D ．向北

高考真题：

12．（2002上海）磁场具有能量，磁场中单位体积所具有的能量叫做能量密度，其值为Ｂ２／2μ，式中Ｂ是磁感应强度，μ是磁导率，在空气中μ为一已知常量。为了近似测得条形磁铁磁极端面附近的磁感强度Ｂ，一学生用一根端面面积为Ａ的条形磁铁吸住一相同面积的铁片Ｐ，再用力将铁 片与磁铁拉开一段微小距离Δｌ，并测出拉力Ｆ，如图图3-2-3所

示，因为Ｆ所做的功等于间隙中磁场的能量，所以由此可得磁感应

强度Ｂ与Ｆ、Ａ之间的关系为Ｂ＝___________。

图

3-2-2 图3-2-3

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新概念英语2一课一练.doc

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完整版新概念2一课一练41 50

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新概念第二册一课一练Lesson29

Less on 29 Taxi 用所给单词或短语的正确形式填空。 2. She _______________ his invitation to the tea party. 3. Nobody likes to live in that _______________ region. 4. Children were watching the planes take off and _______________ . 5. Who can turn clouds into wings and ________________ me to the Palace of Forgett ing? 根据汉语提示完成下列句子。 1. “对不起，这是VIP停车场，只有奔驰和宝马可以在这儿停，明白吗？”保安员说完白 了杰克一眼。 “lam sorry. This is a VIP ________________ where only Benz or BMW can park. Understand? ” The guard sent him an arrogant look. 2. 你可以在冰雪地中开车不代表我们也能。 Just because you can drive _______________ and ice does not mean we can. 3. 他们不是仅仅孤立地看到一幢楼，而是把影响它的各种因素都考虑进去。 They are not only isolated to see __________________ , but the impact of its various factors is take n into acco unt. 从[A]、[B]、[C]、[D]四个选项中，选出可以填入空白处的最佳选项。 1. —I drove to Zhuhai for the air show last week. —Is that you had a few days off? (1999 全国咼考卷) [A] why [B] whe n [C] what [D] where 2. What she couldn ' t understand was fewer and fewer stude nts showed in terest in her less ons. [A] what [B] that [C] why [D] because 3. —Where have you bee n rece ntly? —I in Beiii ng on bus in ess for a week last month [A] was [B] have bee n [C] had been [D] had stayed 4. Where' s my pen? 1 remember leav ing it on the desk. W_o it? [A] took [B] has take n [C] had take n [D] would take 选择正确的词或短语完成句子。 1. His office teleph one nu mber is _____ (that, what) I want to know. 2. As we all know, all _______ (that, which) can be done has been done. 3. His main problem right now is _______ (why, whether) he should ask for another loa n. 4. I _______ (visited, had visited) my parents once a week when I worked in Beijing. 5. I _______ (didn ' t see, haven ' t seen) him since I _________ (have graduated, graduated) from the uni versity. 1

新概念英语2 Lesson6一课一练

Lesson6一课一练 一、词汇 1.There is always a___________（乞丐）in front of my house. 2.I am going to__________(拜访)at my grand father’s house this weekend. 3.He took a pen out of his__________(衣服口袋)and began to write. 4.Would you like some__________(食物)or drink? 5.My__________(邻居)is a very old and nice woman. 6.Someone__________(敲门)at the door when we were having dinner. 7.He__________(返回)to his house last Monday. 二、用a\the\some填空 1.There is_________young man under the tall tree. 2.I bought_________tea in the shop yesterday afternoon. 3.The teacher said,“Look at__________picture on the blackboard.” 4.I met__________old friend of mine in the park last Friday. 5.John sent__________presents to his friends yesterday. 6.There is__________letter“t”in the word“white”. 三、单线选择 1.The clock__________six when I opened the door. A.knocks B.beats C.was knocking D.was beating 2.He bought_________new car_________day before yesterday. A.the;a B.a;the C./;the D.a;a 3.He telephoned me and__________an English dictionary. A.asked for B.put on C.took out D.gave up 4.I will call__________Mary_________her house to tell her my plan. A.at;on B.on;at C.at;at D.on;on 5.Tom helped me a lot with my work.___________,I gave him a present. A.In turn B.In fact C.In public D.In return 6.The boy is standing__________his head and singing songs. A.on B.by C.with D.over 7.Mr Smith said that he had been to Shenzhen___________. A.once a month B.after a month C.long ago D.long before 8.His mother was ill and he had to__________her at home. A.look for B.look up C.look after D.look at 9.Which of the following sentences is wrong? A.I find English difficult to learn. B.I find that English is difficult to learn. C.I find it difficult to learn English. D.I find that is difficult to learn English 10.We still have___________milk,but we don’t have___________coffee at all. A.any;any B.any;some C.some;some D.some;any

新概念英语第二册一课一练lesson 3 word版

Lesson 3 I 根据括号内所给的汉语提示写出相应的英语单词，并注意运用其正确形式。 1.Yesterday I (寄) a present to my sister who is in another city. 2.Timmy (借) a pen to me last week. 3.There is not a (一个的) word on the整个的paper. 4.I stayed at home the (博物馆) day. 5.They went to that (友好的) the day before yesterday. 6.The old man gave me a (决定) smile. 7.He made a big (公共的) on that day. 8.She often goes to that (损坏) park near her house. 9.The heavy rain (服务员) in a restaurant for many years. II 用括号中所给动词的正确形式填空。 1.I (send) a postcard to my friend Tom yesterday. 2.He (go) to the school library every day. 3.The old man (live) there since 1978. 4.The film (begin) before we got there. 5.I (not understand) what he said just mow. III 单项选择（从A,B,C和D中选出最佳选项）。 ( ) 1. You shouldn’t smoke and make such big noise public. A.in B. on C. at D. for ( ) 2. I am sorry that I can’t such a big decision at the moment. A.plan B. do C. make D. work ( ) 3. What you had done my plan completely. A.has spoilt B. had spoilt C. spoilt D. spoilts ( ) 4. My mother was very angry me and began to shout at me. A. at B. in C. for D. with ( ) 5. Would you please some money me? I want to buy a new bag. A. borrow; to B. lend; to C. borrow; from D. lend; from ( ) 6. Tom is very friendly others.

(完整版)新概念一课一练第二册L14word版

Lesson 14 I 根据括号内所给的汉语提示写出相应的英语单词，并注意运用其正确形式。 1.There are a lot of different （语言）in the world. 2.These two boys kept talking loudly during the (旅行). 3.I asked him a question and he (回答) to me immediately. 4.What the old man told us just now is very (有趣的). 5.On the way home yesterday, a man gave me a (搭便车). II 用括号中所给动词的正确形式填空。 1.We (paint) the house before we (move) in. 2.The thief (run away) before the policeman (arrive). 3.I (turn off) all the lights before I (go) to bed. 4.Paul (go) out with Jane after he (make) a phone call. 5.Tom (say) he (read) the book twice. III 单项选择（从A,B,C和D中选出最佳选项）。 ( ) 1. This story everybody in the room. A. amused; amused B. amused; amusing C. amusing; amused D. amusing; amusing ( ) 2. I the problem until he explained it. A.understood B. didn’t understand C.hadn’t understood D.had understood ( ) 3. Could you please me a lift to that small village? A.give B.make C.take D.do ( ) 4. If you cannot my e-mail, please let me know. A.replying B.answer to C.reply to D.answering ( ) 5. He in the factory for three years before he joined the army. A.has worked B.works C.had worked D.will work ( ) 6. Jim had turned off all the lights he left the classroom. A.after B.until C.since D.before ( ) 7. I saw a boy stealing something from a woman the way home today. A.on B.in C.by D.to ( ) 8. He is an tourist(旅行者) and he has a great many interesting .