初三物理电学总复习题
物理电学复习题 (二)
一、单项选择题
1、如图1所示的电路中小灯泡正常发光(若将小灯泡和电流表的位置对换，则( ) A.小灯泡不会发光 B.小灯泡会被烧坏
C.电流表示数不变 D.电压表示数不变
2、如图2所示 A、B是同种材料制成的电阻，它们的长度相等，A的横截面积是B的两 倍，将它们串联在电路中，则加在A、B上的电压U、U和通过A、B的电流I、I间的关系ABAB正确的是( )
A(I=I B(I >I C(U=U D(U>U ABABABAB
L 1
V1 L 2
V 21 S
图1 图2 图3 3、如图3所示的电路，电源电压不变，闭合开关S后，电灯L、L都发 光，一段时间后，12
其中一盏电灯突然熄灭，电压表V的示数变大，电压表V的示数变小，则产生这一现象12
的原因是( )
A(灯L灯丝烧断了 B.灯L灯丝烧断了 12
. 灯L短路 D.灯L短 C12
4、通过直接感知的现象，推测无法直接感知的事实，是常用的物理方法。下列根据现象所
作出的推测不符合事实的是 ( )
A(相同电压作用下通过的电流 推测 电阻的大小
B(电路中的灯泡发光 推测 电路中有电流
C(小磁针放在磁体旁受力偏转 推测 磁体周围有磁场
D(街边的路灯同时亮、灭， 推测 路灯是串联的
5、物理研究中常常会用到“控制变量法”、“等效替代法”、“类比法”、“模型法”等研究方
法，下面用到“等效替代法”的是 ( )
A(研究磁场时，引入了磁感线来描述磁场
B(研究电流与电压关系时，控制电阻不变
C.研究电压时，我们可以通过对比水压来认识它
D(研究两个阻值为R的电阻串联时，可用一个阻值为2 R的电阻来代替 6、如图4所示，电源电压不变，开关S闭合，滑动变阻 器R的滑片P 向右移动时，电表1
的示数变化情况是 ( )
A(电流表示数增大，电压表示数增大 R R 21 B(电流表示数减小，电压表示数减小 A V S C(电流表示数增大，电压表示数减小
D(电流表示数减小，电压表示数增大 图4 7、有两个额定电压相同的灯泡,它们的灯丝电阻分别为R和R,且R
分析
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图象可知，小灯泡正常工作时的灯丝电
阻为_______
(3)从图象还可以看出，小灯泡灯丝的电阻随电压的增大逐渐_______(填“变大”或“变
小”)，从物理学角度分析，造成这一现象的原因是_______。
(4)实验中测出了小灯泡在多次不同电压下的灯丝电阻，有些同学认为可以进一步求出它
们的平均值以减小误差。你是否同意他们的观点,请说明理由。
(5)该实验的整套装置还可以用于其他实验，请举出一例。_______。 1764629791.docof vision Yibin formation in the Center surrounded by, organic dispersion band of bead-space layout structure, as leading devel第 3 页 共 5 页 opment of the city to the East along the Yangtze River. Shi Gu area, lingang new vision to expand, Naxi district to the North, the East open places to expand, Jiang an eastward connection, Ping Shan, radiation to the West; the South Bank area, the minjiang River area, Golden Sands area on a long-term basis in a reasonable space to develop, perfect urban district along the Yangtze River in Yibin "Ribbon multi-center" strategic vision of space frame. Yibin Center City development construction steering extension type extended and connotation type upgrade simultaneously of mode, in Metro construction of while is committed to old city transformation and built district of perfect, through live and industry with to of reasonable layout optimization city structure, improve city traffic operation efficiency; vigorously improved city environment, shaping city features, upgrade city quality, play city of service function, formed has perfect modern service capacity of big city. Construction of urban green space system, promoting the construction of peripheral green space and protection of historical
25、在测“小灯泡电阻”的实验中，电源是两节干电池串联，小灯泡的额定电压是2.5V，小
灯泡正常发光时的电阻约为 8Ω，小刚同学连接的实物电路如图甲所示。 (1) 同组的小明同学在检查线路时，发现有一根导线连接错误。请你在图中用“×”标
出这根错接的导线，并画出改接后的导线(不能与其他导线交叉)。
1 2 P C D 3 0 0.4 0.2 A B 0 0.6 A 0.6 3 — 图乙 第26题图甲
(2)闭合开关前，应将滑动变阻器的滑片滑到______端。(选填“,”或“,”) (3)将变阻器的滑片滑到正确位置后，用开关进行了“试触”，这样做的目的是_ _ _ _。
(只有一个选项正确，将正确选项前的字母填在横线上)
A(选择电流表的量程 B(选择电压表的量程
C(检查电路是否正常 D(观察小灯泡是否发光
(4)某次测量时，电压表的示数是2.5V，电流表的示数如图乙所示。则小灯泡的电阻约为
_______Ω。(计算结果保留小数点后两位)
26、如图10所示，是小明设计的某调温电热器工作原理的甲、乙两个
方案
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，其中电阻R、1
R、R、 R均为发热电阻。(1)甲方案中，开关S、S均闭合，电热器处于高温档;乙2341
方案中，开关S，S1均闭合，电 热器处于_________ 档。(2)甲、乙两种方案中高温档
的功率相同，低温 档的功率也相同，则电阻R_________ R。(选填“,”、“,”或“=”)13
(3)甲方案中，高温档功率是低温档功率的10 倍，若把R换成'2R，结果低温档功率2
变为原来的一半，则'2R=_________R。 1
图10 27、甲、乙两同学分别做“测定小灯泡的电功率”实验，他们使用的器材中，电源电压相同
且不变，滑动变阻器上都标有“20Ω 2A”字样，待测的两个小灯额定电流均为0.35安。
甲同学正确连接电路，闭合电键后，移动滑动变阻器的滑片，当小灯正常发光时，电压
表的示数如图11(a)所示，此时滑动变阻器的滑片恰好在中点(即它接入电路的电阻
为10欧)。乙同学连接电路后，闭合电键，移动滑动变阻器的滑片，当小灯正常发光时，
电压表示数如图11(b)所示，且观察到乙同学的小灯比甲同学的小灯亮。 (1)请画出乙同学连接的电路图 ;(2)甲同学所测小灯的额定功率P= 瓦; 额甲,3,求乙同学所测小灯的额定功率P 瓦。 额乙
of vision Yibin formation in the Center surrounded by, organic dispersion band of bead-space layout structure, as leading development of the city to the East along the Yangtze River. Shi Gu area, lingang new vision to expand, Naxi district to the North, the East open places to expand, Jiang an eastward connection, Ping Shan, radiation to the West; the South Bank area, the minjiang River area, Golden Sands area on a long-term basis in a reasonable space to develop, perfect urban district along the Yangtze River in Yibin "Ribbon multi-center" strategic vision of space frame. Yibin Center City development construction steering extension type extended and connotation type upgrade simultaneously of mode, in Metro construction of while is committed to old city transformation and built district of perfect, through live and industry with to of reasonable layout optimization city structure, improve city traffic operation efficiency; vigorously improved city environment, shaping city features, upgrade city quality, play city of service function, formed has perfect modern service capacity of big city. Construction of urban green space system, promoting the construction of peripheral green space and protection of historical
图11 (a) (b)
1764629791.docof vision Yibin formation in the Center surrounded by, organic dispersion band of bead-space layout structure, as leading devel第 5 页 共 5 页 opment of the city to the East along the Yangtze River. Shi Gu area, lingang new vision to expand, Naxi district to the North, the East open places to expand, Jiang an eastward connection, Ping Shan, radiation to the West; the South Bank area, the minjiang River area, Golden Sands area on a long-term basis in a reasonable space to develop, perfect urban district along the Yangtze River in Yibin "Ribbon multi-center" strategic vision of space frame. Yibin Center City development construction steering extension type extended and connotation type upgrade simultaneously of mode, in Metro construction of while is committed to old city transformation and built district of perfect, through live and industry with to of reasonable layout optimization city structure, improve city traffic operation efficiency; vigorously improved city environment, shaping city features, upgrade city quality, play city of service function, formed has perfect modern service capacity of big city. Construction of urban green space system, promoting the construction of peripheral green space and protection of historical
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