(1)在“多用电表的使用”实验中,如图甲所示,为一正在测量中的多用电表表盘。如果用电阻挡“
”测量,则读数为___________
。
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/13/1bc4e33a-7992-4576-ac54-a4f2404135aa.png?resizew=356)
(2)甲同学利用多用电表测量电阻。他用电阻挡“
”测量时发现指针偏转角度过小,为了得到比较准确的测量结果,请从下列选项中挑出合理的步骤,操作顺序为___________ (填写选项前的字母)。
A.将选择开关旋转到电阻挡“
”的位置
B.将选择开关旋转到电阻挡“
”的位置
C.将两表笔分别与被测电阻的两根引线相接完成测量
D.将两表笔短接,调节欧姆调零旋钮使指针指向“
”
(3)如图乙所示,为简单欧姆表原理示意图,其中电流表的满偏电流
,内阻
,滑动变阻器
的最大阻值为
,电池的电动势
,内阻
,图中与接线柱
相连的表笔颜色应是___________ 色(选填“红”或“黑”),若按正确使用方法测量电阻
的阻值时,指针指在刻度盘的正中央,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/67c1313842b62428737610b14806d883.png)
___________
。
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d55519bd96aba05e6f1533ddc7bb63fa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cffa35373ec4e4684107b42adb7a5161.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/13/1bc4e33a-7992-4576-ac54-a4f2404135aa.png?resizew=356)
(2)甲同学利用多用电表测量电阻。他用电阻挡“
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/eebdb972b35aaa81a6662aaf8db1c282.png)
A.将选择开关旋转到电阻挡“
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d0dca1955e5e2618d2f0e6f0b979ca88.png)
B.将选择开关旋转到电阻挡“
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d55519bd96aba05e6f1533ddc7bb63fa.png)
C.将两表笔分别与被测电阻的两根引线相接完成测量
D.将两表笔短接,调节欧姆调零旋钮使指针指向“
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/712d27c04fb168ca677643b4adad95a9.png)
(3)如图乙所示,为简单欧姆表原理示意图,其中电流表的满偏电流
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/035e7fe40a3ae4b514551727dfe476d4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/592cc8b938d242dbcde27e978a73b1f1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4aa0df7f1e45f9de29e802c7f19a4f64.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/80b83e1d413d48afddd05d9b6b182815.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1d945368499bfc901be3d60cbcdac557.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9fef7ab7166b566761cb79353e7fb88d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ff4489d9b83072184c0e1d6b09be50ca.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ce2581ae160692cd7e2686226fe5e2c6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/67c1313842b62428737610b14806d883.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bb076e4b23c82f7f402ab38730d19890.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/2/13/4a8e99e8-07a9-4af6-921f-880bc0e71773.png?resizew=194)
更新时间:2023-02-13 16:09:12
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【推荐1】某多用电表欧姆挡的内部电路如图甲中虚线框内所示,小明同学将电阻箱和电压表V并联后接在两表笔a、b上,欲用图示的电路测量欧姆挡“×1”时多用电表内部的电阻r(远小于电压表V的内阻)和电池的电动势E。实验的主要步骤为:
![](https://img.xkw.com/dksih/QBM/2020/4/16/2442897283358720/2443475552854016/STEM/a38da7e9-96da-4eba-96da-34cf31e066a7.png?resizew=553)
(1)表笔b为________ (填“红表笔”或“黑表笔”)。将选择开关转至欧姆挡“×1”,将红、黑表笔短接,调节________ ,使指针指在________ (填“左”或“右”)侧零刻度线处。
(2)改变电阻箱R的阻值,分别读出6组电压表和电阻箱的示数U、R,将
、
的值算出并记录在表格中,作出
图线如图乙所示。
(3)根据图线得到电动势E=________ V,内阻r=________ Ω。(结果保留三位有效数字)。
(4)由于电压表的分流作用,多用电表内部电池的电动势的测量值比真实值________ (填“大”或“小”)。
![](https://img.xkw.com/dksih/QBM/2020/4/16/2442897283358720/2443475552854016/STEM/a38da7e9-96da-4eba-96da-34cf31e066a7.png?resizew=553)
(1)表笔b为
(2)改变电阻箱R的阻值,分别读出6组电压表和电阻箱的示数U、R,将
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3424173db742a4d95adaa12141ead673.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dc4cdfc40e3ceea825100c49f43d08a6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3aeb6aba8168ec93e46a14e027651cb4.png)
组数 | 1 | 2 | 3 | 4 | 5 | 6 |
0.02 | 0.04 | 0.06 | 0.08 | 0.10 | 0.12 | |
0.84 | 1.05 | 1.26 | 1.48 | 1.62 | 1.82 |
(4)由于电压表的分流作用,多用电表内部电池的电动势的测量值比真实值
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【推荐2】某电学实验兴趣小组结合物理课本上的多用电表结构示意图及实验室现有器材,设计了如图所示的电路,整个电路装置既可以当
和
的电流表使用,也可以当作两个倍率的欧姆电表使用。他们使用到的器材有:
电源
(电动势
,内阻忽略不计)
定值电阻![](https://staticzujuan.xkw.com/quesimg/Upload/formula/46cfcb890869761aa705eb0441e45018.png)
电流表
(量程为
,内阻
)
滑动变阻器
(最大阻值为
)
单刀双掷开关![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cbb7c747df90b1246e67ed4952aa2809.png)
(1)按照多用电表的构造和原理,接线柱
端应该接______ 表笔(选填“红”或“黑”);
(2)当单刀双掷开关
拨到
端可作为电流表使用,
拨到1端时,此时装置可作为______
(选填“1”或“10”)量程的电流表;
(3)电阻![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8225d0531fba46cbb4a3af4dd2d6751f.png)
______
,电阻![](https://staticzujuan.xkw.com/quesimg/Upload/formula/76986e6f96cbb9d7d6d0fbcf0bf2321a.png)
______
;
(4)将单刀双掷开关
拨到A端可作为欧姆表使用,若
拨到2端,此时作为欧姆挡
倍率,则将
拨到1端时的倍率为______ (选填“
”或“
”)。
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8265201bce13a51a204ff4ff77230a08.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52637d2e7d8a5a0ecdcf56510613a81.png)
电源
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1d945368499bfc901be3d60cbcdac557.png)
定值电阻
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/46cfcb890869761aa705eb0441e45018.png)
电流表
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/895dc3dc3a6606ff487a4c4863e18509.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bf73bb52f4be4583a7f932f36b64af5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f4fe9444aad9e6718ab9643ad1694b2a.png)
滑动变阻器
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4aa0df7f1e45f9de29e802c7f19a4f64.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ffc518da6d0ec136b76d65154b29c650.png)
单刀双掷开关
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cbb7c747df90b1246e67ed4952aa2809.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/27/7437de13-4970-4e17-944c-acd6f0325d45.png?resizew=144)
(1)按照多用电表的构造和原理,接线柱
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
(2)当单刀双掷开关
![](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/530f5b63e797195906285c0c03eb9276.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/58b5bd7cf13ef88690281ce09f1d3471.png)
(3)电阻
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8225d0531fba46cbb4a3af4dd2d6751f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0047f659c182291c84c224df6b5e993f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/76986e6f96cbb9d7d6d0fbcf0bf2321a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0047f659c182291c84c224df6b5e993f.png)
(4)将单刀双掷开关
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/910f1655703721b51006b887a2394b6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/779629f16056a50f4c06e3996d8e1c82.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/eebdb972b35aaa81a6662aaf8db1c282.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/530f5b63e797195906285c0c03eb9276.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d55519bd96aba05e6f1533ddc7bb63fa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d0dca1955e5e2618d2f0e6f0b979ca88.png)
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【推荐3】图a为某同学组装完成的简易多用电表的电路图。图中E是电池,R1、R2、R3、R4和R5是定值电阻,R6是可变电阻;表头G的满偏电流为100μA,内阻为450Ω。虚线方框内为换挡开关,A端和B端分别与两表笔相连。该多用电表有5个挡位,5个挡位为:直流电压1V挡和5V挡,直流电流1mA挡和2.5mA挡,欧姆×100Ω挡。
![](https://img.xkw.com/dksih/QBM/2022/1/7/2896339545251840/2896498169716736/STEM/2c67456c-75ed-4c53-9236-7642b111a74c.png?resizew=262)
![](https://img.xkw.com/dksih/QBM/2022/1/7/2896339545251840/2896498169716736/STEM/8d51c1ac-15ba-4fa4-a29d-d16ab8b5478c.png?resizew=344)
![](https://img.xkw.com/dksih/QBM/2022/1/7/2896339545251840/2896498169716736/STEM/03ea4ff7-1f0c-4e3c-af2d-b2e6e6f16296.png?resizew=134)
(1)图a中的B端与________ (填“红”或“黑”)色表笔相连接;
(2)根据题给条件可得R1+R2=_______ Ω。
(3)某次测量时该多用电表B端是与“1”相连的,指针位置如图b所示。则读数为________ mA;
(4)某次利用多用电表欧姆挡探测一个不含电源的黑箱中元件,如图c,已知黑箱中只有两个元件,且分别在A、B和A、C之间。当红、黑表笔分别接在A、B时,指针首先向右摆动,然后又慢慢地向左回归至“∞”位置;将红、黑表笔分别接在A、C,指针指在“∞”位置,将红、黑表笔分别接在C、A,指针指在“0”刻线偏左一点。在图c的黑箱图中画出电学元件_________ 。
![](https://img.xkw.com/dksih/QBM/2022/1/7/2896339545251840/2896498169716736/STEM/2c67456c-75ed-4c53-9236-7642b111a74c.png?resizew=262)
![](https://img.xkw.com/dksih/QBM/2022/1/7/2896339545251840/2896498169716736/STEM/8d51c1ac-15ba-4fa4-a29d-d16ab8b5478c.png?resizew=344)
![](https://img.xkw.com/dksih/QBM/2022/1/7/2896339545251840/2896498169716736/STEM/03ea4ff7-1f0c-4e3c-af2d-b2e6e6f16296.png?resizew=134)
(1)图a中的B端与
(2)根据题给条件可得R1+R2=
(3)某次测量时该多用电表B端是与“1”相连的,指针位置如图b所示。则读数为
(4)某次利用多用电表欧姆挡探测一个不含电源的黑箱中元件,如图c,已知黑箱中只有两个元件,且分别在A、B和A、C之间。当红、黑表笔分别接在A、B时,指针首先向右摆动,然后又慢慢地向左回归至“∞”位置;将红、黑表笔分别接在A、C,指针指在“∞”位置,将红、黑表笔分别接在C、A,指针指在“0”刻线偏左一点。在图c的黑箱图中画出电学元件
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【推荐1】要该小组研究了导体电阻与其影响因素的定量关系之后,想测定某金属丝电阻率,现有如下器材:
A.干电池两个(内阻忽略不计),导线若干,开关一个
B.电流表
(量程0.6A,内阻约0.1
)
C.电流表
(量程3A,内阻约0.05
)
D.电压表
(量程3V,内阻约3
)
E.电压表
(量程15V,内阻约15
)
F.待测电阻
(约为3
)
G.滑动变阻器
(0~10
)
H.滑动变阻器
(0~200
)
(1)用螺旋测微器测量该导体的直径D,示数如下图所示,可读出D=__________ mm;
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/20/23f50409-1dff-4211-92e5-2cf2aecab4ce.png?resizew=225)
(2)将多用电表调到“欧姆挡×1”,将红、黑表笔短接,进行欧姆调零后,将红、黑表笔分别接触待测导体的两端,多用电表示数如上图所示,则待测电阻,
约为__________
。
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/20/d51f5c71-78d3-4331-9769-d6067e2b8d43.png?resizew=306)
(3)根据你的选择,在图虚线框内设计实验电路图并标出所用器材符号。( )
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/20/422b5c02-7bde-4e3c-8bca-17a7d1900900.png?resizew=188)
(4)实验中,如果两电表的读数分别为U和I,测得圆柱形导体的长度为L,直径为D,则待测电阻丝的电阻率
的计算式为![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b30db97c39edcede2f0e7d4e075fecec.png)
__________ 。
A.干电池两个(内阻忽略不计),导线若干,开关一个
B.电流表
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/024e2379c58191758f8bd7602a6bcb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cffa35373ec4e4684107b42adb7a5161.png)
C.电流表
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b34a75c2a392f235c5f07b91d9fb58d5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cffa35373ec4e4684107b42adb7a5161.png)
D.电压表
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48fade4e14bf5845ff14f9e95bb6bfef.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bb076e4b23c82f7f402ab38730d19890.png)
E.电压表
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b40f1d184152aa3954752ed70e7d1612.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bb076e4b23c82f7f402ab38730d19890.png)
F.待测电阻
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ce2581ae160692cd7e2686226fe5e2c6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cffa35373ec4e4684107b42adb7a5161.png)
G.滑动变阻器
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9efc18a5bb2e53586331b2a58538a48b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cffa35373ec4e4684107b42adb7a5161.png)
H.滑动变阻器
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/19f20f21a9d50b61dac519a3ddab539d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cffa35373ec4e4684107b42adb7a5161.png)
(1)用螺旋测微器测量该导体的直径D,示数如下图所示,可读出D=
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/20/23f50409-1dff-4211-92e5-2cf2aecab4ce.png?resizew=225)
(2)将多用电表调到“欧姆挡×1”,将红、黑表笔短接,进行欧姆调零后,将红、黑表笔分别接触待测导体的两端,多用电表示数如上图所示,则待测电阻,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ce2581ae160692cd7e2686226fe5e2c6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cffa35373ec4e4684107b42adb7a5161.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/20/d51f5c71-78d3-4331-9769-d6067e2b8d43.png?resizew=306)
(3)根据你的选择,在图虚线框内设计实验电路图并标出所用器材符号。
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/20/422b5c02-7bde-4e3c-8bca-17a7d1900900.png?resizew=188)
(4)实验中,如果两电表的读数分别为U和I,测得圆柱形导体的长度为L,直径为D,则待测电阻丝的电阻率
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/171102a883b22fe6ca578efc8926f5b8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b30db97c39edcede2f0e7d4e075fecec.png)
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【推荐2】某同学想通过实验测量某定值电阻的阻值。
(1)用欧姆表测该电阻阻值,选择
挡,短接调零,测量时指针如图甲所示,则该电阻的阻值为_______________
。
(2)为准确测量电阻的阻值,该同学选用了下列器材:
A.电压表![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ec54d4f62e9a593958a49bdccfc2c4c1.png)
B.电流表![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b5a87bf3dad5a30c8740a61c15c789e4.png)
C.电流表![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d3637b8ecef1ee2ab7fcdfc45debf2dc.png)
D.滑动变阻器
(
,额定电流
)
E.电阻箱
,额定电流![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1f64b84ad563a56e0cb1c6bb75baa2d8.png)
F.直流电源![](https://staticzujuan.xkw.com/quesimg/Upload/formula/64de2b14ba81a2cbedab6dcb310a0bd3.png)
G.开关两个、导线若干
为避免电表内阻对测量结果的影响,设计了如图乙所示的电路,其中
为待测电阻,操作过程如下:
a.按电路图连接好电路;
b.
断开,将
的滑片滑至_______________ (填“左端”、“中间”或“右端”),将
调至_______________ (填“最大阻值”或“最小阻值”),闭合
;
c.调节
,使电流表
的示数恰好是
示数的一半;
d.闭合
并保持
不变,读取
示数,分别记作
。
则待测电阻的准确阻值为_______________ ;该同学要将电阻箱阻值由
调至
,应如何操作:_______________ 。
(1)用欧姆表测该电阻阻值,选择
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d55519bd96aba05e6f1533ddc7bb63fa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0047f659c182291c84c224df6b5e993f.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/7/26/78b4acfd-2f5f-4748-9964-98a9ffc44f22.png?resizew=481)
(2)为准确测量电阻的阻值,该同学选用了下列器材:
A.电压表
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ec54d4f62e9a593958a49bdccfc2c4c1.png)
B.电流表
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b5a87bf3dad5a30c8740a61c15c789e4.png)
C.电流表
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d3637b8ecef1ee2ab7fcdfc45debf2dc.png)
D.滑动变阻器
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9efc18a5bb2e53586331b2a58538a48b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d3fe7f473a67ee2367ffbd8bec067b44.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d73c327d0f1396ddc8f8a4c1662cd626.png)
E.电阻箱
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/77e57cbc9ef5625f3ba4ecbf6a36e317.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1f64b84ad563a56e0cb1c6bb75baa2d8.png)
F.直流电源
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/64de2b14ba81a2cbedab6dcb310a0bd3.png)
G.开关两个、导线若干
为避免电表内阻对测量结果的影响,设计了如图乙所示的电路,其中
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4aa0df7f1e45f9de29e802c7f19a4f64.png)
a.按电路图连接好电路;
b.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/530f5b63e797195906285c0c03eb9276.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9efc18a5bb2e53586331b2a58538a48b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/19f20f21a9d50b61dac519a3ddab539d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d43eb0b274e00cbbc4a210da4165042.png)
c.调节
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/46cfcb890869761aa705eb0441e45018.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/024e2379c58191758f8bd7602a6bcb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b34a75c2a392f235c5f07b91d9fb58d5.png)
d.闭合
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/530f5b63e797195906285c0c03eb9276.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/19f20f21a9d50b61dac519a3ddab539d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4f3aaa1083cf5daf57889fb9f41a0dd2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e3d2423f54c69ad015296d48a0e0256a.png)
则待测电阻的准确阻值为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1b577465edb567825864e491d4923d8a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4d75462c4b49707dd41749d8db10f573.png)
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【推荐3】(1)多用电表测未知电阻阻值的电路如图(a)所示,电池的电动势为E、内阻为r,R0为调零电阻,Rg为表头内阻,电路中电流I与待测电阻的阻值Rx关系图象如图(b)所示(用R0表示调零电阻有效阻值即可),则该图象的函数关系式为___________ (要求用以上各量表示)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/8/15/ff688562-86e5-4fc4-8c52-d3c64331798e.png?resizew=291)
(2)下列根据图(b)中I-Rx图线做出的解释或判断中正确的是_________ 。
A.用欧姆表测电阻时,指针指示读数越大,测量的误差越小
B.欧姆调零的实质是通过调节R0,使Rx=0时电路中的电流I=Ig
C.Rx越小,相同的电阻变化量对应的电流变化量越大,所以欧姆表的示数左密右疏
D.测量中,当Rx的阻值为图(b)中的R2时,指针位于表盘中央位置的左侧
(3)由I-Rx图线知,欧姆表内电源电动势为_________ ;
(4)某同学想通过另一个多用电表中的欧姆挡,直接去测量某电压表(量程10V)的内阻(大约为几十千欧),欧姆挡的选择开关拨至倍率______ 挡(填×1,×1k,×10k)。先将红、黑表笔短接调零后,选用图c中________ (填“A”或“B”)方式连接。在本实验中,如图d所示,某同学读出欧姆表的读数为______ 。
![](https://img.xkw.com/dksih/QBM/editorImg/2022/8/15/0b6e0aa3-2aab-4426-8679-2fcf0cacce48.png?resizew=529)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/8/15/ff688562-86e5-4fc4-8c52-d3c64331798e.png?resizew=291)
(2)下列根据图(b)中I-Rx图线做出的解释或判断中正确的是
A.用欧姆表测电阻时,指针指示读数越大,测量的误差越小
B.欧姆调零的实质是通过调节R0,使Rx=0时电路中的电流I=Ig
C.Rx越小,相同的电阻变化量对应的电流变化量越大,所以欧姆表的示数左密右疏
D.测量中,当Rx的阻值为图(b)中的R2时,指针位于表盘中央位置的左侧
(3)由I-Rx图线知,欧姆表内电源电动势为
(4)某同学想通过另一个多用电表中的欧姆挡,直接去测量某电压表(量程10V)的内阻(大约为几十千欧),欧姆挡的选择开关拨至倍率
![](https://img.xkw.com/dksih/QBM/editorImg/2022/8/15/0b6e0aa3-2aab-4426-8679-2fcf0cacce48.png?resizew=529)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/8/15/7f78975e-f70c-4d03-b945-a9d67f90fe43.png?resizew=286)
您最近一年使用:0次