初中物理培优教程电学测试题附答案

Pushing ahead, East, North, West development, facilitating shanty, complete xincheng West Road, stability and reconstruction of the street, Star Ding garden built century Garden District, subject public housing construction, heating the gas expansion accelerated implementation, Jing Rui River and bridge style line solid shaft, further expanded the town development. Beautiful country adhere to the advance and typical for a group to lead. According to ecological lay based, and industry increased income, and live upgrade civilization, and culture rich connotation of thought, caught built beautiful village, and whole village advance, and easily relocation, and five modified three built, project near 30 a; depth into ecological, and industry, and culture, and tourism, elements, high standards caught party original city Liu, and jade are Xia AO, model village, in province City set has benchmark. Four is equal benefits to promote sharing, coordinated development of various social undertakings. In the case of rigid spending slowing revenue growth, increase, financial 75% to the peoples livelihood, the masses have more access in the sharing. Cuoban something good and benefit. Adhere to the affordable, best, carefully cuoban village oil, water and heat, cultural, city and County columns practical, developments benefit families, bring more welfare to the masses. Development of social convenience. Acceptance of balanced development of compulsory education through the national assessment, the County vocational education center was named top School of vocational education in China, the third batch of national reform and development model through provincial . Five is to deepen reform and innovation to break bottlenecks and endogenous development of effective fire. As an engine of dynamism, adding reform key to adopting reform measures stress energy and break bottlenecks and promoting development. Pay close attention to the key areas of reform. Conscientiously implement the provincial deployment and cancel, adjustment, to undertake the administrative approval items according to Regulation 347 to further improve administrative efficiency continuing deepening reform for poverty alleviation, speeding up rural land right registration certification pilot project, encouraging the orderly transfer of land management, utilize the land resources, in order to promote scale management laid the Foundation. Actively cultivate the market. Firmly establish a market-oriented, nurturing family farms, industrial users, professional cooperation organization new market management main body 456, effectively improve the industry, intensive and marketization of encouraging support social capital into the small micro-credit, urban development, culture and tourism, public services and other areas, easing development shortfall. To promote mass innovation. To support the rural sector to use new thinking and new ideas, creative work incentives such as actively promoting financial intermediation, bring added 159 in non public enterprises, individually-1540, created a初中科学培优（电学）测试题 1.两只灯泡L1和L2的额定电压相同，额定功率之比P1P2=21，并联后接在电路中总电流为3安培，则通过L1的电流为_安；若将两只灯泡L1和L2串联后，仍接在原来的电路中，则通过L1的电流为_安。 2.物理小组制作了一个自动控制器，其中有一个调压电路如右图所示，滑动变阻器R的最大阻值是100欧，负载电阻R的阻值为100欧，A、B间电压为10伏，保持不变。使用过程中发现这个电路的调压范围和原设计不符，检查结果是图中F处导线折断，滑动头P由上向下移动时，如果电路完好，CD两端的电压范围应是_伏至_伏；如果F点导线折断，CD两端的电压范围是_伏至_伏。3.闭合开关后，用手按住玩具电动机的转子，不让它转动，这时与电动机并联的电压表读数为3伏，与电动机串联的电流表读数为6安松手后，电动机正常转动，此时电流表读数为1安这台电动机正常转动时，每秒钟有 焦的电能转变为机械能。 4.在右图所示的电路中，当电路两端加上电压U后，电路正常工作.如果电阻R2发生了断路，电阻R3两端电压将减少二分之一，而电阻R2发生断路前电阻R1和R2的总功率与电阻R2发生断路后电阻R1的功率相等。则三个电阻的阻值之比R1:R2:R3为_ _；在电阻发生断路前后，R3上消耗的电功率为_(选填：“变大”、“变小”或“不变”) 5.如图所示，AB和CD是两根固定且平行的水平金属导轨，符号表示垂直于纸面向里的磁场的磁感线。现将铜棒EF和GH垂直放在滑轨上，当拉动GH使其向左移动时，发现EF也向左移动，请你说明此过程中所包含的物理知识： ；若拉动EF使其向右移动时，GH应向 (选填“左”或“右”)移动。6.工人师傅在改装电炉时，要使电功率减小到原来的一半，下列措施中可行的是：截去一半电炉丝； ( )串联一条相同的电炉丝；并联一条相同的电炉丝；把连接电炉和电源的导线长度增加一倍。7.如图电源电压恒定在滑片P由a滑至b的过程中，电压表的读数 （ )A先减小，后增大 B先增大，后减小 C不断增大 D不断减小8. 右图中当变阻器滑片P向右滑动时，两电压表读数变化应是 （ ) A. V1增大，V2增大； B. V1减小，V2减小； C. V1增大，V2减小； D. V1减小，V2增大。 9.现有两个用电器，上面分别标有“6V，0.2A”和“12V，0.5A”的字样，如果把这两个用电器串联起来，为了使其中的一个用电器正常工作，那么加在串联电路两端的电压应该是（ ）A. 9.4 V，B. 10.8 V，C. 18 V，D. 27 V。 10.某同学连接的电路实物图如图所示。闭合电键后，灯泡L1、L2都不亮，他用电压表进行电路故障检测，测试结果如左下表所示，则电路中的故障是( ) 测试点 a、b c、d d、f电压表示数有示数无示数有示数A灯泡L1短路。 B灯泡L2短路。Ccd段断路。 Ddf断路。 11.如右下图是从某电子仪器拆下来的密封盒子。已经知道盒内有三只电阻， 、B、 为四根引线，现用多用电表测量，得知 间的电阻 AC欧，间的电阻 CD=50欧， 间的电阻 AD欧。若用导线把 连接后，测得间电阻AD欧，请在方盒内画出电阻的连接图，并在图中标出每个电阻的阻值。12.山区某工地施工时，照明电路需用导线从离工地250米处的电源引来，工地上要用一只“220V100W”和一只“220V200W”的灯泡来照明，所用导线的电阻为每米0.018欧，如果电源两端的电压为220伏，且保持不变，试求照明时导线上所消耗的功率和每只灯泡实际所消耗的功率。（计算时不考虑灯丝电阻的变化） 13.冬天，太阳能热水器水箱中水温较低。小华在水箱中加装了一个“220 V， 2000 W”的电热管，并利用一个“6 V， 1W”的小灯泡和一段10/m的电阻丝，为电热管安装了一个指示灯。（1）在下面虚线框中画出电热管及指示灯的电原理图。（2）在小华同学的方案中，小灯泡两端的电压是按5V设计的。对于指示灯来说，这样设计有什么好处？（3）按上述设计，电阻丝需截用多长的一段？（4）安装指示灯后，电热管的实际功率是额定功率的百分之几？（计算中可以认为电热管。小灯泡及电阻丝的电阻不随温度发生明显的变化，数值只取整数，小数可四舍五入）。 14.如图所示电路，电源电压不变，R1=12，小灯泡标有“6V12W”（电阻不变）。求：（画出下列每小题的等效电路图） (1)只闭合Sl时，电流表示数为08A，则电源电压为多大？ (2)当Sl、S2、S3都闭合时，将滑片P移动到b端，电流表的示数为12A，则滑动变阻器的最大阻值是多少？ (3)只闭合S2时，移动滑片P，使滑动变阻器所消耗的功率为它最大功率的3/4此时电流表的示数是多少？ 15.有一个特殊结构的元件(如图14所示)，由A、B两部分组成，被封闭在透明的玻璃壳内，a、b为两个接线柱。某学生为了研究A、B两部分电学特性，通过查阅资料，得知A是一个定值电阻，其U-I值如表1；B是一种由特殊金属丝制成的导体，该元件的额定电压是7伏。为了既不破坏元件的结构，但又能测定B的额定功率，他使用如图15所示的器材，测得一组该元件的U-I值(如图16所示)后，利用这些数据测出了B的额定功率。请你回答以下问题：图14图15图16表1U(V)0.52.54.56.58.510.51(10-3A)5.024.845.065.285.0104.8(1)用笔线代替导线，将如图15所示的器材连接成一个测量元件的U-I值的电路。(2)请利用表1和如图16提供的数据求出B在正常工作时的额定功率P。初中科学培优（电学）测试题 答案1.2A 0.67(2/3)A 2. 10 0 10 5 3. 2.5 4. 12:4:9 变小 5.电磁感应；通电导体在磁场中受力的作用 右 6. B 7. A 8.D 9.B 10.C20306011. 12.1 5瓦；90瓦；1 80