为了研究“I与U、R”的关系,小红设计了如图所示的电路,进行如下一系列实验. (

题型:问答题

问题:

为了研究“I与U、R”的关系,小红设计了如图所示的电路,进行如下一系列实验.

(1)小红在研究“导体中的电流跟电阻的关系”时,步骤如下:

“保持电源电压不变,闭合开关,换用不同的电阻.调节滑动变阻器滑片位置,记录对应的电流表示数”,实验数据见下表:

次数第1次第2次第3次
R/Ω51015
I/A0.30.20.1
由此,小红得出结论:______.

小红设计的电路中有错误之处,请在方框中画出正确的电路图.

小红实验步骤中的疏漏之处是:______.

(2)在同学们的帮助下,小红改进了实验,得出欧姆定律.她认为:“根据欧姆定律,可得R=U/I,这说明在电流相同的情况下,同一导体的电阻与该导体两端的电压成正比.”这种说法是______的(正确/错误),理由是______.

(3)下面是小红在测定值电阻Rx电阻时所连接的电路.她连接的实物电路有错误,请在图中将错误之处用“×”表示出来,并用铅笔线代替导线正确地连接电路.

(4)改正后,闭合开关,观察到电流表的示数为0.14A.当她把滑动变阻器的滑片移到中点位置时,电压表、电流表的示数分别为2.5V、0.20A.接着她又移动滑片到某点A,这时电流表的示数如图所示.通过分析可知A点在滑动变阻器中点的______侧(选填“左”或“右”).

考点:探究电流与电压、电阻的关系
题型:问答题
关于万有引力定律及引力常量,下列说法中正确的是(  )

A.万有引力定律揭示了自然界物体间普遍存在的一种基本相互作用--引力作用的规律

B.卡文迪许测得了引力常量,从而证明了万有引力定律的正确性

C.引力常量的单位是N•m2/kg2

D.两个质量为1kg的质点相距1m时的万有引力大小为6.67N

题型:问答题

对筛检的描述正确的是

A.筛检是全科医生为达到早期发现所必须进行的工作

B.筛检可快速把有潜在疾病但表面健康的人与无病的人区别开来

C.筛检既检查又是诊断

D.筛检一般用于慢性病

E.筛检也可用于健康人群

题型:问答题

正向限位是指流槽前端到管模插口端的距离。

题型:问答题

It should go without saying that the focus of UML is modeling. However, what that means, exactly, can be an open-ended question. (71) is a means to capture ideas, relationships, decisions, and requirements in a well-defined notation that can be applied to many different domains. Modeling not only means different things to different people, but also it can use different pieces of UML depending on what you are trying to convey. In general, a UML model is made up of one or more (72) . A diagram graphically represents things, and the relationships between these things. These (73) can be representations of real-world objects, pure software constructs, or a description of the behavior of some other objects. It is common for an individual thing to show up on multiple diagrams; each diagram represents a particular interest, or view, of the thing being modeled. UML 2.0 divides diagrams into two categories: structural diagrams and behavioral diagrams. (74) are u sed to capture the physical organization of the things in your system, i.e., how one object relates to another. (75) focus on the behavior of elements in a system. For example, you can use behavioral diagrams to capture requirements, operations, and internal state changes for elements.

A. views B. diagramsC. user views D. structure pictures

题型:问答题

色谱仪检测器的主要性能指标有()。

A、灵敏度

B、检测限

C、响应时间

D、线性范围

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