1、六年级英语第三单元测试题六年级英语第三单元测试题班级: 姓名:_ 得分_听力部分(30分)一、 听录音,选择你所听到的单词或短语。(10分)( )1.A.do B.did C.does( )2.A.watch B.wash C.watched( )3.A.saw B.short C.see( )4.A.swim B.swam C.swims( )5.A.study B.studied C.studies( )6.A.went B.watched C.go二、听录音,选出你所听到的句子,将其序号填入题前括号里。(10分)( )1. A.hat do you usually do on the w
2、eekend? B.hat did you do on the weekend?( )2.A.Did you go to the park? B.Did you go at night?( )3.A.I went to a park yesterday. B.I visited my grandparents yesterday.( )4.A.u yifan played football with his yesterday.B.u yifan cleaned his room yesterday.( )5.A.He went hiking last weekend. B.She went
3、hiking last weekend.三、听问句,选答语。(10分)( ) 1、A.Yes, I did. B.Yes , I do.( ) 2、A.I read a book. B.last weekend.( ) 3、A.He went swimming . B、She went swimming.( ) 4、A.No, I didnt . B.Sure.( ) 5、A.I usually watch TV. B.I watched TV.笔试部分(70分)一、选择(10分)( )1.-Did you help me clean my room?-Yes,I _.A.did B.do C
4、.does( )2.-hat did Lisa do yesterday?She_ tusic.A.listens B.listen C.listened( )3.- Did you play football hang Peng?A、with B、 and C、to( )4.Tom busy yeaterday.A、did B、 was C、were( )5.Lisa usually her homework after super.A、does B、do C、did( )6. hat _ he _ yesterday ?A. does, do B. do , did C. did, do(
5、 )7._ he _ football last weekend ?A. Did, played B. Did, play C. Did, plays( )8.I_my room last weekend. Alean Bleans Cleaned( )9.Amy usually_her homework after super.A.does B.do C.did( )10. hats the matter? y leg .A.hurt B.hurts C.is hurts二、写出下列单词的过去式。(10分)(1).按求填空。1.发烧2. teach(三单形式)_ 3.tall(反义词)4.h
6、ot(反义词)_5.thin(比较级)_ 6.big(反义词)_7.heavy(比较级) 8hild(复数形式) 9.run(ing形式) 10.sheep(复数形式)_(2)、写出下列单词的过去式watch_study _see _buy _ do _ go _ read _ have_ fly_play_三、从B栏选择A栏的正确答语。(10分) A B( ) 1. hat did he do yesterday ? A. Yes, she did.( ) 2. Did she wash the clothes yesterday ? B. I went fishing .( ) 3. ha
7、t did you do last weekend ? C. No, I didnt .( ) 4. Did you went to the park ?D. He read a book yesterday.( ) 5. hat was the weather yesterday ? E. It was sunny .( ) 6. How tall are you?F. I went to injiang by plane.( ) 7. How do you feel? G. I am 160 cm tall.( ) 8. How did you go to injiang? H. I fe
8、el sick.( ) 9.here did you go last month?I. Last week.( ) 10.hen did you go to Beijing? J. I went to Harbin.四、连词成句。(每个2分,共10分)1、did what you yesterday do 2、did where go you holiday on your 3、went I to park a yesterday 4、jumped the into lake he 5、with ang Ping hisplayed friends last football weekend
9、五、读下列短文,选择正确答案(每题2分,共20分)( A )Today was hot. I went to the farm(农场)with my parents. There was a river near the farm . I went to the river with my dog . e ran and played . Suddenly I dropped(掉进)into the river ,“Help , Help”y dog jumped into(跳进)the river and swam to me , Ten minutes later , I was save
10、d(救)。I was grateful to him. e are good friends.( )1、It was very .A、cold B、hot C、windy( )2、I went to the farm with my .A、parents B、friends C、teacher( )3、I ran and played with .A、my cat B、my dog C、my sister( )4、 jumped into the river and saved me.A、y dog B、y mother C、y father( )5、I was very grateful t
11、o my .A、mother B、friend C、dog( B )It is Saturday morning. rs Black and her daughter ate go to the bookshop Near their house. rs Black wants to buy some picture books for her grandson. ate wants to buy some storybooks. In the bookshop ate meets her old classmate, Sue. They are good friends. They talk
12、 and talk for a long time and forget to buy books. At twelve oclock rs Black finds them and asks Sue to go and have lunch in their house, Sue says: “Yes.” The two girls are very happy.( ) 1. rs Black and her daughter go to the bookshop on Sunday orning.( ) 2. The bookshop is near the school.( ) 3. T
13、he two girls meet in the bookshop.( ) 4. ate forget to buy books.( ) 5. The two girls go and have lunch at twelve oclock.Aa Bb Cc六、写出所缺的字母。(10分) x Yy z 的导线要比原线圈粗,C 错误;居民小区各个用电器都是并联的,它们的电流总和等于副线圈中的电流,故D 错误【答案】 AB11. 如图所示,发电机内部线圈处于磁铁和圆柱形铁心之间的径向磁场中,两半边间的过渡区域宽度很小,可忽略不计线圈的总匝数为N、总电阻为 r,每匝线圈的面积为 S,线圈所在位置的磁
14、感应强度大小为B.当线圈以角速度 匀速转动时,额定电压为U、电阻为 R的小灯泡在电路中恰能正常发光,则发电机产生的感应电动势的有效值是( ) 2ANBS B. 2 NBSrCU D1RU【解析】 根据题述线圈处于磁铁和圆柱形铁心之间的径向磁场中,当线圈以角速度 匀速转动时,产生的交变电流为矩形波,发电机产生的感应电动势的有效值是 NBS,选项 A 正确,B 错误由闭Ur r合电路欧姆定律,EU R 1RU,选项C 错误,D 正确【答案】 AD12. 如图所示,为探究理想变压器原、副线圈电压、电流的关系,将原线圈接到电压有效值不变的正弦交流电源上,副线圈连接相同的灯泡L1、L2,电路中分别接了理
15、想交流电压表 V1、V2 和理想交流电流表A1、A2,导线电阻不计,如图所示当开关S 闭合后( )AA1 示数变大,A1 与A2 示数的比值不变BA1 示数变大,A1 与A2 示数的比值变大C. V2 示数变小,V1 与 V2 示数的比值变大D. V2 示数不变,V1 与V2 示数的比值不变U1 n1【解析】 由U n 知,开关 S 闭合后,V2 示数不变,V1 与 V2 示2 2数的比值不变,故选项 C 错误,选项 D 正确;开关 S 闭合后,副线圈U2 I1 n2闭合回路的总电阻R 减小,由 I2 R 知,I2 变大,由I2n1知,A1 示数变大,且A1 与A2 示数的比值不变,故选项A
16、正确【答案】 AD第卷(非选择题 共 52 分)二、实验题(本题有 2 小题,共 15 分,请将答案写在题中的横线上)13(6 分)为了测定和描绘“220 V 40 W”白炽电灯灯丝的伏安特性曲线,可以利用调压变压器供电调压变压器是一种自耦变压器,它只有一组线圈 L,绕在闭合的环形铁芯上,输入端接在 220 V 交流电源的火线与零线间,输出端有一个滑动触头 P,移动它的位置,就可以使输出电压在 0250 V 之间连续变化,图中画出的是调压变压器的电路图符号实验室内备有交流电压表、交流电流表、滑动变阻器、开关、导线等实验器材(1) 在图中完成实验电路图(2) 说明按你的实验电路图进行测量,如果电
17、表内阻的影响不能忽略,在电压较高段与电压较低段相比较,_ 段的误差更大,因为 【解析】(1) 如图所示开关应安在火线一边(2) 如果采用电流表外接法,电压较高段误差更大,因为电压越高,灯丝电阻越大,由于电压表分流而造成的误差越大;如果采用电流表内接法,电压较低段误差更大,因为电压越小,灯丝电阻越小,由于电流表分压造成的误差越大【答案】 见解析14(9 分)有一个教学用的可拆变压器,如图甲所示它有两个外观基本相同的线圈A、B,线圈外部还可以绕线(1) 某同学用一多用电表的同一欧姆挡先后测量了A、B 线圈的电阻值,指针分别对应图乙中的 a、b 位置,由此可推断 线圈的匝数较多(选填“A”或“B”)
18、(2) 如果把它看成理想变压器,现要测量 A 线圈的匝数,提供的器材有,一根足够长的绝缘导线、一只多用电表和低压交流电源请简要叙述实验的步骤(写出要测的物理量,并用字母表示) _ _ _A 线圈的匝数为 nA_ .(用所测物理量符号表示)【解析】 (1)由图乙可知a 位置的阻值大于 b 位置的阻值,由电阻定律可得A 线圈的匝数多于B 线圈的匝数(2)用长导线绕一个 n 匝线圈,作为副线圈替代A 线圈把低压电源接B 线圈,测得线圈的输出电压U.UA用A 线圈换下绕制的线圈测得A 线圈输出电压UA.nA U nUA【答案】 (1)A (2)步骤见解析 nA U n三、计算题(本题有 3 小题,共
19、37 分,解答应写出必要的文字说明方程式和重要的演算步骤,只写出最后答案的不能得分,有数值计算的题,答案中必须明确写出数值和单位)15(10 分)如图甲所示,在周期性变化的匀强磁场区域内有垂直于磁场的半径为 r1 m、电阻为 R3.14 的金属圆形线框,当磁场按图乙所示规律变化时,线框中有感应电流产生(1) 在图丙中画出感应电流随时间变化的 it 图象(以逆时针方向为正);(2) 求出线框中感应电流的有效值【解析】 (1)如图所示(2)设电流的有效值为 I,则有2 2 T 2 2TI RTi1R3i2R 3得 I 2 A【答案】 (1)见解析 (2) 2 A16.(13 分)如图所示,匀强磁场
20、磁感应强度 B0.5 T,匝数为 n50匝的矩形线圈,绕垂直于匀强磁场的转轴 OO匀速转动,每匝线圈长为L25 cm,宽为d20 cm.线圈每分钟转动 1 500 转,在匀速转动过程中,从线圈平面经过图示位置时开始计时(1) 写出感应电动势 e 的瞬时值表达式;(2) 若每匝线圈本身电阻r0.02 ,外接一阻值为13 的用电器,使线圈与外电路组成闭合电路,写出感应电流 i 的瞬时值表达式;(3) 若从线圈平面垂直于磁感线的位置开始计时,感应电动势 e和感应电流 i的瞬时值表达式如何?(4) 画出(1)(2)中的 et、it 图象【解析】 (1)线圈匝数 n50,磁场的磁感应强度 B0.5 T,
21、线1 500圈转动的角速度 2f2 60 rad/s50 rad/s,线圈的面积 SLd0.05 m2所以 EmnBS500.50.0550 V196 V从图示位置计时,有 eEmcost196cos(50t) V.(2)若 r0.02 ,则 r50 r0.0250 1 R 总 Rr13 1 14 I Em 196m R 14 A14 A总所以 iImcost14cos(50t) A(3) 若从线圈平面与磁感线垂直的位置开始计时,即从中性面开始计时,感应电动势和感应电流的瞬时值表达式分别为e196sin(50t)V,i14sin(50t) A.(4) 因为 50,2所以T 0.04 s,Em1
22、96 V,Im14 A(1)(2)中的 et、it 图象分别如图甲、乙所示【答案】 见解析17(14 分)一台小型发电机的最大输出功率为 100 kW,输出电压恒为 500 V,现用电阻率为 1.8108 m,横截面积为 105 m2 的输电线向 4103 m 远处的用户输电,要使发电机满负荷运行时,输电线上的损失功率不超过发电机总功率的 4%,求:(1) 所用的理想升压变压器原、副线圈的匝数比是多少?(2) 如果用户用电器的额定电压为 220 V,那么所用的理想降压变压器原、副线圈的匝数比是多少?(3) 想一想,当深夜接入电路的用电器减少时,用电器两端的电压是大于、小于还是等于 220 V?
23、若用电器电路中电流为 100 A,求此时用电器两端的电压数值2l【解析】 (1)输电要用两根导线,则输电线的电阻为 r S241031.8108 105 14.4 P 2由题意知P 损P4%U2 r105U1050.042214.4U26 000 Vn1 U1 500 1升压变压器原、副线圈匝数比n U 6 00012.2 2P 105 502(2)I2U 6103 A 3 A50U 损I2r 3 14.4 V240 V而U3U2U 损6 000 V240 V5 760 Vn3 U35 760 288n U 220 114 4降压变压器原、副线圈匝数比为 288 11(3)用电器总数减少时,用电器两端电压将增大由题知 I 100 A 则由I4n3 2884 I3n4 11
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