电源(电动势
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5c70a1dbeebcd2e55059333fa96ccc2f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9db144c76e36b0c4d950698b2bbc39f9.png)
电压表V(量程为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9cd1fc5aefd9457c7ae9fa5acbcdcdd1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/813431bcf2e3dcda7c2139e646811bd6.png)
电流表
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acf35aa115963656d885b6440d6caa2c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4b5c929172bbfc21741fa7ef1f53b7bb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4fc5b25100d880c7526011d1455281a0.png)
电流表
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c9e65b2e896a5c2371ef4d17d58d2709.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9a9d332743ec267382cd99600b757cd3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2e8101844381fdba17f6f22295ba8366.png)
滑动变阻器
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9efc18a5bb2e53586331b2a58538a48b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/510a282f9101ebd5713bb2012ea1fb21.png)
滑动变阻器
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/19f20f21a9d50b61dac519a3ddab539d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7d73e3afd9125734e380b2fe53d0f258.png)
(1)用游标卡尺测得该金属丝的长度如图甲所示,读数为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fd1846e964fd60c54888a3c706a97442.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9a6d85799453899836bc34ad276ec80e.png)
(3)设测得金属丝的电阻为R,可得金属丝的电阻率为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b30db97c39edcede2f0e7d4e075fecec.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a18722354086c42e62334983fc50eb6a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cd3b9e816b14051f785aa5aae72b8eed.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1903fc3c6b9b1347c4c2efbb66fd1501.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be9b4a83b9aebebf29de0c4406ebf894.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a18722354086c42e62334983fc50eb6a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cd3b9e816b14051f785aa5aae72b8eed.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/be9b4a83b9aebebf29de0c4406ebf894.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be9b4a83b9aebebf29de0c4406ebf894.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e3809dcdc5e9eb9e901c827698e04e21.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2f1ac49b4139636fb1809fe970b23a87.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2d1a0fd1ad044a9ecfcba672779bd678.png)
(2)更换同种材料,不同规格的金属丝,分别测量电导,将实验数据汇总如下:
导线直径d(mm) | 1 | 2 | 3 | 2 | 2 | 2 |
导线长度l(cm) | 500 | 500 | 500 | 400 | 250 | 100 |
电导G(S) | 0.25 | 1.00 | 2.25 | 1.25 | 2.00 | 5.00 |
(3)为了测量不同金属的导电性能,该组同学更换适当测量电路,对直径分别为1mm、长度为100 cm的不同金属导线进行了进一步测量,测量不同金属丝电压U和电流I数据汇总如下:
金属 | 铜 | 铝 | 铁 | 钨 |
导线两端电压U(V) | 0.017 | 0.015 | ||
流过导线电流I(A) | 0.05 | 0.1 | 0.15 | 0.2 |
(1)实验小组先用多用电表的欧姆“×1k” 档倍率粗测了水样电阻的阻值,示数如图2,读数为
![](https://img.xkw.com/dksih/QBM/2024/2/29/3443381425242112/3443468152668160/STEM/b1aa84b6048f4defbf12fdbb42980e13.png?resizew=584)
(2)然后实验小组用“伏安法”测量水样电阻的阻值。现有电源(3V,内阻约0.1Ω)、滑动变阻器(0~100Ω)、开关和导线若干,以及下列电表:
A.电流表(0~300 μA,内阻约100 Ω)
B.电流表(0~0.6 A,内阻约0.125 Ω)
C.电压表(0~3 V,内阻约3 kΩ)
D.电压表(0~15 V,内阻约15 kΩ)
为减小测量误差,在实验中,电流表应选用
![](https://img.xkw.com/dksih/QBM/2024/2/29/3443381425242112/3443468152668160/STEM/c30d9860b00f4371b7d31e070c220dfb.png?resizew=668)
(3)实验小组测出水样电阻的阻值为R,用游标卡尺测出装水容器的长度为L,内径为D,则电导率的表达式为
(1)用10分度的游标卡尺测量圆柱体的长度
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0c88d9142df6ba8e43c1a93bd04a1362.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/21f3bf70722b22983c120d008d097602.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/21f3bf70722b22983c120d008d097602.png)
![](https://img.xkw.com/dksih/QBM/2024/1/22/3416785313120256/3420748928983040/STEM/77ca150e8eca4567a5c4362f9a4e661f.png?resizew=218)
![](https://img.xkw.com/dksih/QBM/2024/1/22/3416785313120256/3420748928983040/STEM/0e19354c667d4050b38a5df0986df184.png?resizew=173)
(2)圆柱体的电阻大约为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/77a6041c88c8701ce1068b611f27aa4a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4aa0df7f1e45f9de29e802c7f19a4f64.png)
A.电压表
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4a6bb65878785532d817f8fd11a9ef3d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/80b83e1d413d48afddd05d9b6b182815.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/edaab27d71cd1a342f454c8853e69e4c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3f9df7c4451a17142088a8220917c3b7.png)
C.电流表
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4b5c929172bbfc21741fa7ef1f53b7bb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/47367bf5c848198638bc6d92ebe37262.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5da295ce39cf1df62bac67e0ee57bc1.png)
E.滑动变阻器,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d3fe7f473a67ee2367ffbd8bec067b44.png)
要求较准确地测出其阻值,电压表应选
(3)在测定阻值较小的金属的电阻率的实验中,为了减小实验误差,并要求在实验中获得较大的电压调节范围,在测量其电阻时应选择的电路是
A.
![](https://img.xkw.com/dksih/QBM/2024/1/22/3416785313120256/3420748928983040/STEM/3d7f33798c40417d9bc96089f19967c9.png?resizew=146)
![](https://img.xkw.com/dksih/QBM/2024/1/22/3416785313120256/3420748928983040/STEM/105bc842fab140e3b63bfd38c2f77e89.png?resizew=150)
C.
![](https://img.xkw.com/dksih/QBM/2024/1/22/3416785313120256/3420748928983040/STEM/8428939ecc4a4796a7d687bb95f3337a.png?resizew=154)
![](https://img.xkw.com/dksih/QBM/2024/1/22/3416785313120256/3420748928983040/STEM/bbd1dbae278f4d19a8a7fd31a99bd5d6.png?resizew=156)
(4)若金属丝电阻用
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4aa0df7f1e45f9de29e802c7f19a4f64.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b30db97c39edcede2f0e7d4e075fecec.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be9b4a83b9aebebf29de0c4406ebf894.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b339fea9adaa555b2fe0282fdf804007.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d03deed1577fb72a40ad0abf20c2bd85.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/1/20/505240ef-a4a0-4ab5-823e-d1b6eefbe74e.png?resizew=577)
图中V1和V2均为理想电压表,定值电阻
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9de4f366fa2d18a9811cde2e9b4773b6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d8372335ffadefe3adb9946fd1e7f32.png)
(1)不加外磁场,调节
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d8372335ffadefe3adb9946fd1e7f32.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/59e71ff24143805b6bccc592babda977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f67c8cf659b61acbbf921160e933d5a0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5be4dd62f994aa9b12b4da0ccba9ac60.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cffa35373ec4e4684107b42adb7a5161.png)
(2)加外磁场,调节
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d8372335ffadefe3adb9946fd1e7f32.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/317ae9611ad21b2a996a80ffa0c71385.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f833a7beb83820ecede0234c671f1878.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d03deed1577fb72a40ad0abf20c2bd85.png)
(3)改变B,重复(2)操作,实验数据如下表,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/11f626267206cfa0f944648e198d5388.png)
![]() | … | 0.15 | 0.20 | 0.25 | 0.30 | 0.35 | 0.40 |
![]() | … | 0.56 | 0.59 | 0.62 | ① | 0.69 | 0.72 |
![]() | … | 0.40 | 0.48 | 0.55 | ② | 0.73 | 0.80 |
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/76f08446d04b377b8bbc152b562f8584.png)
6 . 某同学测量某金属丝的电阻率,实验过程如下:
(1)装置安装和电路连接:
如图甲所示。金属丝的一端固定,另一端作为活动端来改变金属丝接入电路的长度,两端分别用带有金属夹A、B的导线接入如图乙所示的电路中。
(2)金属丝电阻率的测量:
①用刻度尺测量并记录A、B间的距离,即为导线的长度。用螺旋测微器测量此时金属丝的直径,示数如图丙所示,其直径为
②将滑动变阻器R的滑片滑到最右端。断开开关,闭合开关
,调节R,使电压表和电流表的指针偏转到合适位置。记录两表的示数
和
。
③闭合,电压表的示数变小。记录两表的示数
和
,则此时金属丝的电阻为
、
、
、
表示)。
④根据电阻定律求得金属丝的电阻率。
⑤断开,增大导线的长度,重复上述步骤,计算出电阻率的平均值。
(3)电压表内阻对该实验的测量结果,下列说法正确的是
A.金属丝电阻测量值一定偏大
B.金属丝电阻测量值一定偏小
C.电压表内阻对金属丝电阻的测量值无影响
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/77a6041c88c8701ce1068b611f27aa4a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac5de0509aedeed60371d11fdea241ac.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/27/d47c8a32-33d8-4e4b-88f9-e8f269d59825.png?resizew=178)
(1)如图为某次测量金属丝直径时螺旋测微器的示数,其测量值
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7c98c59cd4749afdd21e73529fc84323.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/21f3bf70722b22983c120d008d097602.png)
(2)实验室提供的器材有:
A.电压表
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48fade4e14bf5845ff14f9e95bb6bfef.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4a6bb65878785532d817f8fd11a9ef3d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/951f5dfc2ee88b950c0a4322d9236ce4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b40f1d184152aa3954752ed70e7d1612.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/edaab27d71cd1a342f454c8853e69e4c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/549b8489b17608927e9ba3f6d2da1f16.png)
C.电流表
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/024e2379c58191758f8bd7602a6bcb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4b5c929172bbfc21741fa7ef1f53b7bb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dcbf05e437e731c2cb7e5f420d076e25.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b34a75c2a392f235c5f07b91d9fb58d5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9a9d332743ec267382cd99600b757cd3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5d0210026c88ec845716829b24ecc77f.png)
E.滑动变阻器
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4967df2404465f5beb6cf21580986387.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b2dcd67266aebdaf4e073337152b8b82.png)
G.电源
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e3e0a6f3b59a4cca5721ec634408d197.png)
从以上器材中选择合适的器材进行实验,则电压表应选择
(3)要求在流过金属丝的电流相同的情况下,电源的输出功率最小,并能较准确地测出金属丝的阻值,实验电路应选用图中的
A.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/27/d0b54ffe-0b1c-4c37-9171-9a8d6c6c5d8d.png?resizew=121)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/27/b7d4cb51-3046-4a65-9b25-219adf024aee.png?resizew=124)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/27/497da7ea-5c89-4a9b-a521-80601cbd92e5.png?resizew=123)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/27/43c0ccb6-3a14-4c6a-a1bd-891d92fbe00c.png?resizew=135)
(4)实验中测得金属丝电阻为
![](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/104d13a3453c8730d00c3192df071895.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b30db97c39edcede2f0e7d4e075fecec.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9ab545b0f59f88bd054aeb388d85f089.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/12/ef58edad-0a19-4741-bd4c-3b7b9096f83b.png?resizew=566)
(1)小明同学先用多用电表粗测其电阻,将选择开关置于欧姆“
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2468403b3eba9e40bfa36f464e927738.png)
(2)为了准确测量封装筒内封装溶液的电阻,实验室提供了下列器材:
A.干电池两节(每节干电池的电动势约为1.5V,内阻可忽略);
B.灵敏电流表G(量程为0~0.5mA,内阻等于120Ω);
C.电压表V1(量程为0~3V,内阻约为4kΩ);
D.电压表V2(量程为0~15V,内阻约为7kΩ);
E.滑动变阻器R1(最大阻值为10Ω);
F.电阻箱R2(最大阻值为9999.9Ω);
G.开关、导线若干
该同学用伏安法完成测量,除干电池、开关、导线和滑动变阻器R1外,还应选择的电压表是
A.电池组(3V、内阻约lΩ)
B.电流表(0~3A,内阻约0.0125Ω)
C.电流表(0~0.6A,内阻约0.125Ω)
D.电压表(0~3V,内阻约4kΩ)
E.电压表(0~15V,内阻约15kΩ)
F.滑动变阻器(0~20Ω,允许最大电流lA)
G.滑动变阻器(0~2000Ω,允许最大电流0.3A)
H.开关、导线
(1)上述器材中应选用的是
(2)图甲是未完成的实物连线图,图中a为待测导体右端接线柱,b为电流表正极接线柱,c为滑动变阻器左上端接线柱,d为滑动变阻器左下端接线柱。则导线①应连接
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/8/e01d74c2-e054-4c76-8004-f76be9011521.png?resizew=278)
(3)某次用螺旋测微器测金属丝直径为d,用游标卡尺测金属丝的长度为L,电压表和电流表的示数分别为U、I,写出该金属丝的电阻率的表达式
(4)如图乙所示,金属丝的长度L为
![](https://img.xkw.com/dksih/QBM/editorImg/2023/12/8/90b01333-cc30-4765-8240-eb0c83e61b60.png?resizew=322)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/46ad1a9cd19361d1f7a2340d76d50c80.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4c688d3183cdee79c0ce7d84a23a38c4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9efc18a5bb2e53586331b2a58538a48b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7360be2b67b6b5babf34b1b056f736f0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/19f20f21a9d50b61dac519a3ddab539d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/89a817ca4817583fed0801a637a88fd6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4aa0df7f1e45f9de29e802c7f19a4f64.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5d2c733a38ac9dcd28bd0c28c341da8e.png)
①用游标卡尺测量玻璃管的内径
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c0c960fcd49b30cdfd5fe514bca92fdb.png)
②向玻璃管内填满土壤,并测量土壤长度
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0c88d9142df6ba8e43c1a93bd04a1362.png)
③把
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a454a2c91ace8ef50412a6adf91f8086.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48fade4e14bf5845ff14f9e95bb6bfef.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9fd5f9ecb870fedb5b9a608d9ca2f911.png)
④把
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a454a2c91ace8ef50412a6adf91f8086.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b40f1d184152aa3954752ed70e7d1612.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48fade4e14bf5845ff14f9e95bb6bfef.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4aa0df7f1e45f9de29e802c7f19a4f64.png)
⑤改变玻璃管内土壤长度,重复步骤③、④,记录每次土壤长度
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0c88d9142df6ba8e43c1a93bd04a1362.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4aa0df7f1e45f9de29e802c7f19a4f64.png)
⑥断开S,整理好器材。
(1)步骤③中通过土壤的电流为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9fd5f9ecb870fedb5b9a608d9ca2f911.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9efc18a5bb2e53586331b2a58538a48b.png)
(2)步骤④中的
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4c688d3183cdee79c0ce7d84a23a38c4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/626bef2c2a1f9df3771f72edf8116b36.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4aa0df7f1e45f9de29e802c7f19a4f64.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/67c1313842b62428737610b14806d883.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/46cfcb890869761aa705eb0441e45018.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4aa0df7f1e45f9de29e802c7f19a4f64.png)
(3)利用记录的多组土壤长度
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0c88d9142df6ba8e43c1a93bd04a1362.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4aa0df7f1e45f9de29e802c7f19a4f64.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c44f4a09777a224f8fa909e7e2c3338b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/04bd482c8aa483cd59b4c22636960fe0.png)