(2)为减小误差,应选用甲图中的
(3)实验过程中,改变滑动变阻器的滑片位置,并记录两电表的读数,作出如图乙所示的I—U图像,可得金属丝的电阻R =
(4)电路保持闭合,若测量时间较长,会使电阻率的测量结果
![](https://img.xkw.com/dksih/QBM/editorImg/2023/4/17/6093f9c6-d7b9-4fcd-ada5-cad076a1512a.png?resizew=596)
(1)导电金属丝拉伸装置如图1所示,按图2连接电路,将该导电金属丝的A、B两端分别与电路中的C、D两端连接;
(2)在
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0c88d9142df6ba8e43c1a93bd04a1362.png)
(3)保持开关
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/530f5b63e797195906285c0c03eb9276.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d43eb0b274e00cbbc4a210da4165042.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4aa0df7f1e45f9de29e802c7f19a4f64.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b52b4f24969673c863b5aff4fb6751ce.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2f1ac49b4139636fb1809fe970b23a87.png)
(4)闭合开关
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/530f5b63e797195906285c0c03eb9276.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4aa0df7f1e45f9de29e802c7f19a4f64.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b52b4f24969673c863b5aff4fb6751ce.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2d1a0fd1ad044a9ecfcba672779bd678.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/67c1313842b62428737610b14806d883.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2f1ac49b4139636fb1809fe970b23a87.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2d1a0fd1ad044a9ecfcba672779bd678.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b52b4f24969673c863b5aff4fb6751ce.png)
(5)断开开关
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d43eb0b274e00cbbc4a210da4165042.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ce2581ae160692cd7e2686226fe5e2c6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0c88d9142df6ba8e43c1a93bd04a1362.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ce2581ae160692cd7e2686226fe5e2c6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0c88d9142df6ba8e43c1a93bd04a1362.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df780ef963d641d07d1337629e053b7d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5fb9cf838c1ce1e61fbc68f101a15a4d.png)
(6)若上述理论成立,可将导电金属丝作为传感器中的敏感元件来监测构件间的微小拉伸变化。按图3所示电路将该导电金属丝连接在两构件之间,实验中保持电压表读数不变,两构件电阻及电流表内阻可不计,若将电流表刻度改为构件间的距离,则越向左相邻刻度间的数据差值
![](https://img.xkw.com/dksih/QBM/2023/3/31/3206601328082944/3207307097268224/STEM/42463eaafff546ceba0f392421dcefa3.png?resizew=554)
(1)用游标卡尺测量长度L,如图甲所示,L为
(2)由螺旋测微器测量直径d,如图乙可知,d为
(3)新材料制成的圆柱体阻值大约为5Ω,用伏安法测电阻时,由于电压表、电流表内阻有影响,为了减小系统误差,则选择如图丙
4 . 某科技小组为测量一种新型导电材料的电阻率,取一块厚度均匀、上下表面为正方形的该型导电材料,如图1所示。
(1)科技小组用多用电表的欧姆挡粗测该导电材料沿AC方向的电阻。机械调零、欧姆调零后,选择“挡”,按正确的操作步骤测量电阻,表盘的示数如图2所示,则该导电材料沿AC方向的电阻约为
。
(2)实验小组还想更精确地测量该导电材料沿AC方向的电阻,可供选择的实验器材如下:
A.电源(电动势,内阻不计)
B.定值电阻()
C.定值电阻()
D.电流表(量程
,内阻
)
E.电流表(量程
,内阻
)
F.滑动变阻器(阻值范围为
,允许通过的最大电流为
)
G.足量的导线与开关
为使实验误差尽可能小,要求电表的测量值在满偏值的以上,定值电阻应选用
”或“
”)。利用虚线框中电路图精确测量电阻
,在电路图中标明器材符号
(3)实验中测得两电流表、
的示数分别为
和
,可得电阻
(4)要测量该导电材料的电阻率还需要测量该导电材料的
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/9/7e432b46-a1ba-47c4-a6fa-fdfe6d067e95.png?resizew=148)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/9/c0dfa45b-e1f9-425e-b8b0-10c514e32232.png?resizew=306)
(1)螺旋测微器和游标卡尺的示数如上图,则直径为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9a6d85799453899836bc34ad276ec80e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/21f3bf70722b22983c120d008d097602.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fd1846e964fd60c54888a3c706a97442.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/21f3bf70722b22983c120d008d097602.png)
(2)为了测量出该工件的电阻,该同学设计了如图甲所示的电路,请按设计的电路完成实物图乙的连线
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/9/9888fa1f-83fe-4484-84aa-ed9e2af3bf38.png?resizew=650)
(3)如图丙所示,实验中当把电压表的右端分别接于a点和b点,发现电流表的示数有明显的变化.若实验时把电压表的右端接于a点,这时测得的电阻值比真实值偏
(4)实验测得工件两端的电压为U,通过的电流为I,写出该圆柱体工件电阻率的表达式
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b30db97c39edcede2f0e7d4e075fecec.png)
(1)先用螺旋测微器测量电阻丝Rx的直径d,示数如图甲所示,其直径d=
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/28/482c1a3e-c7bd-4aa0-971c-b91898f1f64a.png?resizew=122)
(2)首先用多用电表粗测Rx的电阻,当用“×10”挡时发现指针偏转角度过大,应该换用
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/28/42ea1b8e-0c83-4d88-862d-75cc7637328c.png?resizew=350)
(3)为了能比较精确地测量Rx的阻值,实验室提供了如下的实验器材,电流表应选用
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/28/98f1d524-db6d-44de-ba6f-b0a01ade632b.png?resizew=143)
A.电源(电动势E=6V,内阻不计);
B.电流表(量程为30mA,内阻R1=9.5Ω);
C.电流表(量程为3A,内阻R2=0.1Ω);
D.电压表(量程为6V,内阻RV>10kΩ);
E.定值电阻(R3=0.5Ω);
F.定值电阻(R4=5Ω);
G.滑动变阻器(最大阻值为10Ω,允许通过的最大电流为2A);
H.滑动变阻器(最大阻值为15kΩ,允许通过的最大电流为0.5A);
I.开关S,导线若干。
(4)根据所选用的实验器材,设计测量电阻的电路图如图丙所示,若电压表的示数为U,电流表的示数为I,则待测电阻的计算式为Rx=
(5)则该合金丝的电阻率ρ=
(1)用螺旋测微器测量金属丝直径D时,测量结果如图甲所示,则读数D=
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/21/0fb07e56-5c0a-46e3-876c-78125eaf4dd7.png?resizew=418)
(2)某同学设计了图乙所示的实验电路,调节电阻丝上的导电夹P的位置,用毫米刻度尺测量并记录连人电路的电阻丝的长度x;闭合开关S,记录电压表示数U、电流表示数I;改变电阻丝上的导电夹P的位置,重复测量,记录多组x、U、I的值.根据多组测量得到的实验数据绘出
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a064b2de09b87fd4942b9c625d95411e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5c46981ab8889be2831c518c76feaade.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3f828f17f7bfb993093f9b4641e3c7ee.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/7/29/dbfb534f-b36f-440d-ae6e-47ab7d810797.png?resizew=484)
(1)游标卡尺测量其长度如图甲所示,可知其长度为L=
(2)用螺旋测微器测量其直径如图乙所示,可知其直径为D=
(3)选用多用电表的电阻“×1”挡粗测电阻,按正确的操作步骤测此圆柱体的电阻,表盘的示数如图丙所示,则该电阻的阻值约为
(4)为更精确地测量其电阻,可供选择的器材如下:
![](https://img.xkw.com/dksih/QBM/editorImg/2022/7/29/773c0c82-e137-4781-8118-e67003eefafa.png?resizew=220)
电流表A1量程300mA,内阻约为2Ω;
电流表A2量程150mA ,内阻约为10Ω;
电压表V1量程1V,内阻为1000Ω;
电压表V2量程15V,内阻约为3000Ω;
定值电阻阻值R0=2000Ω
滑动变阻器R1最大阻值为5Ω
滑动变阻器R2最大阻值1000Ω
电源E(电动势约为4V,内阻r约为1Ω)
开关,导线若干。
为了使测量尽量准确,测量时电表读数不得小于其量程的
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4dac452fbb5ef6dd653e7fbbef639484.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fd995178601c2ad7b40f973d268c7bb7.png)
(5)连接电路,测得电压表读数为U,电流表读数为I,则电阻率的表达式为ρ=
![](https://img.xkw.com/dksih/QBM/editorImg/2022/6/29/b1741a31-4aa5-4316-b3ac-0c0c8b288969.png?resizew=517)
(1)用螺旋测微器测量其直径,结果如图甲所示,由图可知其直径为D=
(2)利用如图乙所示的电路精确地测量电阻丝的电阻(其中电流表内阻
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5d6f371b60b8d747433ac85bba13074d.png)
①闭合开关,调节滑动变阻器和电阻箱,使电压表有一较大读数U,记下此时电阻箱的读数
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9efc18a5bb2e53586331b2a58538a48b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2f1ac49b4139636fb1809fe970b23a87.png)
②改变电阻箱的阻值,同时调节滑动变阻器,使电压表的读数仍为U,记下此时电阻箱的读数
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/19f20f21a9d50b61dac519a3ddab539d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2d1a0fd1ad044a9ecfcba672779bd678.png)
③重复步骤②,得到多组电阻箱和电流表的数据,以电阻箱电阻R为横坐标,以电流表电流的倒数
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/963a73a661a554bbf37cc74d702ccea0.png)
A.20分度的游标卡尺
B.螺旋测微器
C.电流表A1(0~100mA,内阻约为10Ω)
D.电流表A2(0~0.6A,内阻约为0.1Ω)
E.电压表V1(0~3V,内阻约为3kΩ)
F.电压表V2(0~15V,内阻约为15kΩ)
G.直流电源E(4V,内阻不计)
H.滑动变阻器R(0~5Ω,2A)
I.开关及导线若干
(1)用游标卡尺测得该样品的长度L。其示数如图甲所示,其读数为
![](https://img.xkw.com/dksih/QBM/2022/4/29/2968474763411456/2968619937947648/STEM/1cf5cf60-42df-4558-8aa6-937acee6a00a.png?resizew=398)
(2)本次实验的电流表选用的是
(3)为尽量精确测量新型圆柱形的导电材料的电阻R0应采用下图中的
![](https://img.xkw.com/dksih/QBM/2022/4/29/2968474763411456/2968619937947648/STEM/92a07602-3d9b-4eca-b32c-3d5c3c456552.png?resizew=494)