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考研课习题 6955

根据真空中的高斯定理,判断下列说确的是

有关电场强度的说确的是

关于静电场中p、q两点的电势差,下列说确的是

场强相等的区域,电势也处处相等;场强为零处,电势一定为零。

在等势面上移动电荷,电场力不做功。

电荷在电场力作用下运动时,其电势能总是 的。

已知电场中a、b两点的电势分别为u1和u2,在将电荷q从b点移动到a点的过程中,电场力所做的功等于

1、电场中某点场强的方向,就是将点电荷放在该点所受电场力的方向。( )

沿电场线的方向是电势降落的方向。( )

电容各为c的两个电容器并联,总电容为

下列说法中错误的是

如果某带电体电荷分布的体电荷密度r增大为原来的2倍,则电场的能量变为原来的

如图,一接地导体球外有一点电荷q,q距球心为2r,则导体球上的感应电荷为

导体a接地方式如图,导体b带电为 q,则导体a

径不等的两金属球a、b ,ra = 2rb ,a球带正电q ,b球带负电2q,今用导线将两球联接起来,则

如图,半径为r的金属球壳内有一个点电荷q,金属球壳本身不带电,当点电荷q沿着图中虚线(该虚线通过球的中心)由左向右在球壳内运动时,球壳外p点的电势将

关于导体和电介质,下面说确的是

两同心薄金属球壳,半径分别为r1,r2(r2>r1)若分别带上电量q1,q2的电荷,则两者电势分别为u1、u2,现用导线将两球壳连接,则它们的电势为:

平行板电容器接入电源保持两板间电压不变,将两板间距拉大,则电容器各量的变化为

下列说确的是

一运动电荷q,质量为m,以初速v0进入均匀磁场,若 v0与磁场方向的夹角为a,则

如图匀强磁场中有一矩形通电线圈,它的平面与磁场平行,在磁场作用下,线圈发生转动,其方向是

如图13.3所示的电路,设线圈导线的截面积相同,材料相同,则o点处磁感应强度大小为

一个电流元idl放在磁场中的某点,当它沿x轴放置时不受力,如把它转向y轴正方向时,则受到的力沿z轴负方向,则磁感应强度b的方向为

有两条无限长直导线各载有5a的电流,分别沿x、y轴正方向流动,在点(0.4、0.2、0)处b是

有一半径为r的单匝圆线圈,通以电流i,若把该导线弯成匝数n=2的平面圆线圈,导线长度不变,并通以同样的电流,则线圈中心的磁感应强度和线圈的磁矩分别是原来的

如图,流出纸面的电流为2i,流进纸面的电流为i,则下述各式中哪一个是正确的是

如图,矩形载流线框受长直载流导线产生磁场的作用将:

一圆线圈直径为200px,共12匝,通有电流5a,将此线圈置于磁感应强度为0.6t的均强磁场中,求作用在线圈上的最大磁力矩为多少?

设将通有电流i的无限长导线弯成如图形状,求圆心o点处的磁感应强度。

根据法拉第电磁感应定律,闭合回路中的感应电动势的大小依赖于

一根无限长直导线载有i,一矩形线圈位于导线平面内沿垂直于载流导线方向以恒定速率运动(如图),则

下列说法错误的是

将形状完全相同的铁环和橡胶环静止放在交变磁场中,并假设通过两环面的磁通量随时间变化率相等,不计自感,则有

若尺寸相同的铁环与铜环所包围的面积中穿过相同变化率的磁通量,则在两环中

如图所示,均匀磁场被局限在无限长圆柱形空间内,且成轴对称分布,图为此磁场的截面,磁场按db/dt随时间变化,圆柱体外一点p的感应电场ei应

细长螺线管的截面积为50px2,线圈总匝数n=200,当通有4a电流时,测得螺线管内的磁感应强度b=2t,忽略漏磁和两端的不均匀性,则该螺线管的自感系数为

位移电流的实质是

如图,匀强磁场b中,长为l的直导线与水平方向夹角为放置,并以与水平方向成角匀速运动,则导线中的动生电动势将

无限长直导线通有电流i位于纸面内,ab、bc、cd为光滑裸导线(电阻为零)构成矩形的三边,电阻为r的光滑裸导线ef放置在abcd上而构成回路ebcf,其中bc、ef与i平行且间距分别为a、b,现让导线ef以速度v水平向右运动,求1、图中回路ebcf中的磁通量?2、回路中的感应电动势。

下列说确的是

下列说确的是

两质点a和b,质量分别为ma和mb (ma>mb),速度分别为va和vb(va>vb),受到大小相同的冲量作用,则下列说确的是

描述质点位置随时间变化的快慢和方向的物理量是 。

质点运动时,如果只有切向加速度,没有法向加速度,那么物体作 运动。

根据力做功的性质可分为保守力和非保守力, 力做功与路径无关。

物体具有保持原有运动状态的性质叫 。

功率的国际单位是 。

为了安全,在公路上行驶的汽车之间应保持必要的距离,已知某高速公路的最高限速为108km/h.假设前方车辆突然停止,后车司机发现这一情况立即操纵刹车,刹车时汽车受到阻力的大小为汽车重力的0.40倍,若司机的反应时间是0.50s,该高速公路上汽车间的距离至少应为多少米?

如图所示,物体a重ga=40n,物体b重gb=20n,a与b、b与地的动摩擦因数相同。用水平绳将物体a系在竖直墙壁上,水平力f向右拉物体b,当f=30n时,才能将b匀速拉出。求a与b、b与地的接触面间的动摩擦因数多大?

如图所示,质量m=2.0kg的物体沿着固定的四分之一圆形轨道,从a点由静止开始下滑到b点时的速度为6.0m/s。已知圆形轨道的半径为4m。求:(1)物体从a点下滑到b点过程中摩擦力所做的功;(2)物体在运动过程中所受的平均阻力。(取g=10m/s2)

为了安全,在公路上行驶的汽车之间应保持必要的距离,已知某高速公路的最高限速为108km/h.假设前方车辆突然停止,后车司机发现这一情况立即操纵刹车,刹车时汽车受到阻力的大小为汽车重力的0.40倍,若司机的反应时间是0.50s,该高速公路上汽车间的距离至少应为多少米?

如图所示,物体a重ga=40n,物体b重gb=20n,a与b、b与地的动摩擦因数相同。用水平绳将物体a系在竖直墙壁上,水平力f向右拉物体b,当f=30n时,才能将b匀速拉出。求a与b、b与地的接触面间的动摩擦因数多大?

如图所示,质量m=2.0kg的物体沿着固定的四分之一圆形轨道,从a点由静止开始下滑到b点时的速度为6.0m/s。已知圆形轨道的半径为4m。求:(1)物体从a点下滑到b点过程中摩擦力所做的功;(2)物体在运动过程中所受的平均阻力。(取g=10m/s2)

第一题:为了安全,在公路上行驶的汽车之间应保持必要的距离,已知某高速公路的最高限速为108km/h.假设前方车辆突然停止,后车司机发现这一情况立即操纵刹车,刹车时汽车受到阻力的大小为汽车重力的0.40倍,若司机的反应时间是0.50s,该高速公路上汽车间的距离至少应为多少米? 第一题问1:司机从发现到踩刹车,汽车前进的距离为 m.

第一题问2:刹车后车的加速度为 m/s2

第一题问3:汽车刹车后通过的距离为( )m.

第一题问4:该高速公路上汽车间的距离至少应为( )m。

第一题问:司机刹车后汽车做( )运动。

10c的点电荷在电场中某点受到的电场力为10n,20c的点电荷在该点受到的电场力为( )n.

在点电荷形成的电场中,某一点距场源电荷为r,当r→0时,根据点电荷场强公式e=kq/r/r,则下列正确的是( )

将耐压相同电容值不同的两个电容器串联组成电容器组,当串联电容器组两端电压无限升高时,先击穿的将是( )

两根相互平行无限长金属线载有相同方向的电流,这两根导线将( )

如图所示,线圈两端接在电流表上组成闭合电路,在下列过程中,线圈内没有感应电流产生的是( )

电场强度大处,电势也一定高;电势高处,电场强度一定大。

带电粒子在电场中一定受到电场力的作用。

因电容定义式为c=q/u,所以,当电容器不带电时,q=0则c=0。

带电粒子进入磁场中,一定会受到磁场的作用力。

导体在磁场中运动时,一定产生感应电动势。

电场强度和电势是描述电场两方面性质的物理量, 是描述电场力方面性质的物理量。

将导体放在电场中,导体最终将处于 状态。

将电介质放在电场中将产生 现象。

磁场、电场都是由电荷产生的,但 只能由运动电荷产生。

磁感应强度的国际单位是 。

第二题问3:c2= μf。(用实数表示,保留二位小数)

第三题问2:图中直电线2在o点产生的磁感应强度为 t。

winston churchill achieved fame for his wit, wisdom, civic duty, and abundant courage.

albert einstein and thomas edison were both very art in their childhood.

abraham lincoln's abundant courage enabled him to succeed despite all the misfortunes in his life.

sandra day o'connor was rejected from the law circuit because she was from a poor family.

according to the author, many artists, writers and stateen achieve prosperity because they are very lucky.

most cities in the country have introduced "clean air zones" _____ factories and households are only allowed to burn okeless fuel.

he knows that the ______ of social status can consume vast amounts of his time and effort.

the doctors are at a loss because so far no medicine has been found to _____ the spread of the disease.

thomas edison is often cited as an example of a great inventor who would never yield to hardships in his quest for new inventions and deserve his _____ success.

they are ______ of unconventional attitudes toward marriage and the changing roles of the sexes.

she was totally wrapped ____ in her painting whenher father came to tell her that there was a phone call for her.

when his mother was in the hospital producing his sister, he was very excited - _____ anticipation of having a cute baby sister.

most scientists in the world today firmly believe the effective means to stop global warming is to reduce emissions of air _____.

earthquakes have plagued our lives and resulted in great damage to the human beings for as long as people have ____ the earth.

miss world organizers claim on their official website that ____ are judged on qualities other than just their physical appearance.

after being grabbed off the street by nazis, audrey hepburn escaped because she was unbelievably beautiful.

as an anonymous refugee, audrey hepburn was totally baffled by life’s horrors and fragility.

audrey hepburn valued academy awards most.

when she was trying to complete her missions, audrey had to provide a lot of emotional care and was always confronted with dangerous tasks.

audrey emphasizes the inborn beauty of a person which can never be acquired in growth and cultivation.

news media worked overtime to ________ the country as open and "ready" for all nuclear discussions.

we provided information to site administrators about typical functions of ________ library programs.

we just go on in our habitual ways until we are stopped short by one of the many illnesses that ________ our civilization today.

then you do believe in god, but you guess that i do not, and you fear that the admission of your true belief would ________ your chance of employment.

mrs. cummins, very ________ in her duties, watched the whole process with a sensitive eye.

look, we're about to ________ the last and final stage of our academic careers together.

to promote particular organizational values, and encourage high levels of informal communication, the managers can attempt to lead ________ example.

one reason that i may be the last person in manhattan without a cell phone is that i ________ the excitement of coming home and finding a call light flashing.

when you get the right role, you want to stay focused; you want to ________ yourself as much as you can.

the burdensome trip described in para. 1 is to deny the benefits of modern aviation.

according to para's 2-4, we travel not because we need to, but because we want to.

people travel to leave all their troubles behind, however, ironically, their mind is most likely to solve their most difficult problems when they are in a distant place.

travelling can help loosen the cognitive chains that imprison us and can grant us new and open insights into the world around us.

that people need distance and differences for creativity is the real purpose why people travel.

it was all too easy, when one was young, to ________ the future in the excitement of the present.

it will be noted that the improved visibility of this warning light does not completely ________ the increased tendency to make an error during the night.

it is difficult to ________ of such thinking taking place without the growth and development of intellectual ability.

the world of the ________ is to do with success, status, respect, money, desires of all kinds, and fears, that lead to unhappiness.

just as women now demand for themselves greater freedom to express different ________ of themselves, so too do some men, although not nearly so many of them.

one of the features of auto-immune diseases is that they ________ within iniduals and sometimes within an inidual's family.

competition for limited resources is an inevitable feature of life so long as reproduction occurs in the context of ________ supplies.

in studying children's pictures, a wide variety of ________, personal, and cultural factors needs to be taken into account.

if the product does absorb moisture or ________ water, discard it.

the author uses the example of "an obese child" to vividly prove that westerners think chinese parents raise kids without courtesy.

the western parents want to protect their children from critici because they worry about their children's worries instead of their bad performance.

chinese parents demand perfect grades because they believe that substandard performance is a reflection that the kids do not work hard enough, and will not be successful in the future.

western parents think that children are not born because they want to come to this world. instead, their parents force life on them. children don't owe their parents anything.

according to the author, western parenting method is more beneficial to children's success in the future because parents try to respect their children's iniduality and provide a positive and nurturing environment for them.

now it is a national charity employing 20 people centrally and ________ the work of 400 coordinators employed around the country.

it is ridiculous that a man who has no claim on the world's attention should nonetheless be able to exact (强求) full ________ from his wife.

it advises artists to ________ from oking or eating while painting, to use face masks and to provide adequate ventilation (通风) by means of an extractor fan.

the committee was satisfied that minor incidents of misconduct or ________ of the chairman had been well handled by the directors within the rules.

the form of social control is more ________, aiming to reintegrate children and families into society rather than to rescue children and punish parents.

it was not simply a matter of exporting enough to pay for necessary imports, as contemporary economic ________ often suggested.

but just how long it takes for the heat to flow out will depend on how well your home is ________ and draught proofed.

what they contested was the ________ that moral reform could be achieved through a centralized program.

waller was argumentative, ________, and sometimes outspoken, but he had a sense of humor and he retained a childlike delight in science throughout his life.

it was clear that some of the disturbances were triggered by the ________ actions of local residents.

下面各项,通过生命表无法获得的是 。

据lotka-volterra种间竞争模型,两个相互竞争的种群出现稳定共存的条件是 。

运用逻辑斯谛增长模型,渔、牧业领域可收获的最大持续产量是rk/2。

k-选择者较r-选择者一般寿命长,个体大。

下面不属于生态因子发挥作用一般特征的是 。

下图绘出了5种鱼的耐盐范围和耐温范围。在这5种鱼中哪一种是北极海的特有种,哪一种只生活在热带湖泊中,哪一种的分布最广泛? 。

春天繁殖的动物是长日照动物。

常温动物的体温是固定不变的。

生物对气候环境因子的耐受范围决定其分布范围。

请搜集园林设计中常用的耐阴植物分别从乔木、灌木和草本三种生活型各给出3-5种植物。

请阐述“植物私生活”视频中植物与光因子之间关系的现象2-3例;

下面可用来判定小兽是否适应缺水生境的最明显性状是 。

影响冬小麦春化作用的主导因子是 。

下面属于淡水硬骨鱼渗透压调节特征的是 。

东北虎体型比华南虎大符合阿伦规律。

外温动物与植物完成某一阶段的发育,需要一定的总热量。

下面种间关系中属于专性互利共生的是 。

yoda氏-3/2自疏法则描述的规律发生在 。

粘液瘤病毒引进澳大利亚几年后毒力逐渐减弱,原因是 。

适度放牧可提高草原的生物量。

竞争释放指的是缺乏竞争者时物种扩张其实际生态位的现象。

下列关于生物群落的叙述正确的是 。

在地区尺度上物种组成沿着某个梯度方向从一个群落到另一个群落的变化率称为:

物种多样性指数的高低取决于 。

组成群落的种类越丰富,用于计算群落物种数目的最小面积就越小。

物种多样性指的是物种数目的丰富度。

在植物群落的发展变化过程中,一个群落由另一个群落取代的过程叫 。

生物多样性不包括下列哪一项 。

中等强度的干扰有利于高生物多样性的维持。

植物群落的形成,可以从裸地上开始,也可以从已有的另一个群落中开始。

演替顶极指每一个演替系列都由先锋阶段开始,经过不同的演替阶段,到达中生状态的最终演替阶段。

生态系统中连接有机物质和无机环境的两个重要环节是 。

在下图四个数量金字塔中,哪一个与植物→蚜虫→食蚜瓢虫的食物链相符合?

n 1营养级所获得的能量占n营养级获得能量之比称为 。

相比中度干扰,较大程度的干扰往往导致生态系统具有更高的物种多样性。

在生态系统中,食物链是能量流动的渠道。

下列哪项属于非地带性植被 。

藤本植物和附生植物在下列哪种群落中最常见 。

一般来说,大陆型的植被垂直带谱,每一个带所处的海拔高度,比海洋型同一带的高度要高。

植被分布的纬向地带性主要是由水分为主导因素的不同而形成的。

生态系统是由生产者、消费者和无机环境构成的。

在繁殖过程中,出现特殊的复大孢子繁殖的藻类是

异形胞与一般营养、生殖细胞相比,为颜色浅淡的一种特殊细胞,仅存于

没有细胞核的藻类为

浮游藻类共有几个门?

蓝藻的特征色素是什么?

常见的针杆藻属于硅藻门中的哪个目?

臂尾轮虫的咀嚼器是属于

具左旋口缘小膜带(唇带)的纤毛虫是

运动胞器为伪足,壳由外界环境中的泥砂微粒或硅藻空壳粘合而成的原生动物为

能进行套筒式伸缩的轮虫种类为

绝大多数枝角类滤食器官为

桡足类的常见生殖方式属于以下哪种类型

短沟蜷属于

属于双壳类古异齿亚纲的种类为

生态学忍耐性相对较窄,是水流无污染程度较好的指示昆虫,并且幼虫是许多鱼类饵料的是

属于梭子蟹科的种类

以下不属于海洋污损生物的是

当今世界三大养殖虾类中养殖面积和产量最大的对虾养殖品种、对虾属中最大型种是

以下哪种水生维管束植物不是草食性鱼类的优质食物

以下哪种水生维管束植物是在秋冬季节生长,在夏季休眠

以下哪种水生维管束植物没有异形叶

以下哪种水生维管束植物的耐低光能力相对较强?

以下哪种植物属于挺水植物类型

水葫芦的营养繁殖方式为

藻类定性采集的主要工具是什么?

浮游植物定量采集的工具是什么?

底栖动物定量采集的工具是什么?

池塘藻类的定量计数通常是在多少倍显微镜下操作的?

底栖动物从底泥中采集后,用什么工具帮助筛选?

以下哪个选项,在提高藻类计数过程中的操作不正确?

在繁殖过程中,出现特殊的复大孢子繁殖的藻类是

异形胞与一般营养、生殖细胞相比,为颜色浅淡的一种特殊细胞,仅存于

运动胞器为伪足,壳由外界环境中的泥砂微粒或硅藻空壳粘合而成的原生动物为

绝大多数枝角类滤食器官为

短沟蜷属于

属于双壳类古异齿亚纲的种类为

以下哪种水生维管束植物是在秋冬季节生长,在夏季休眠

以下哪种植物属于挺水植物类型

藻类定性采集的主要工具是什么?

浮游植物定量采集的工具是什么?

下列哪一项不是社会保障学科的特点?

“社会保障”对应的英文表达是?

社会保障的本质是什么?

“老有所终,壮有所用,幼有所长,鳏、寡、孤、独、废疾者、皆有所养。”这段话来自于下列哪部著作?

社会保险制度的建立的标志性事件是?

社会救助制度的建立的标志性事件是?

城乡最低生活保障制度属于下列哪一类社会保障计划?

相传夏禹提出"调有余而补不足",那么请问这对应于现代社会,体现了的何种职能?

下列哪一个不是德国新历史学派的主张或特点?

马克思著名的“扣除说”出自他的哪一部名著?

关于罗斯福《社会保障法案》表述正确的是:

针对英国19世纪济贫法改革表述错误的是:
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