如图,电源电动势
,内阻
,
、
为两个可调电阻。已知电动机的额定电压
,线圈电阻
。开关S闭合后,可调电阻
取
、
取
时,电动机恰能正常工作,则电动机正常工作时的效率![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1b789a2028e8068fad522b48c8180a41.png)
_______ 。在电动机正常工作的前提下调节电阻
、
的取值,则电源输出功率能达到的最大值为________ 。
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b2c6cf7103ca3f8b26022ccba1a1cb5c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/111f7b77e5c3e77b9e00cd99813abe50.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/d0b8638e200e0aedab8624a63156f791.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2ab09c0568231813611cee3fc2cd7d57.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9efc18a5bb2e53586331b2a58538a48b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9db144c76e36b0c4d950698b2bbc39f9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/19f20f21a9d50b61dac519a3ddab539d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c8f08ec4eeb21903011205b600d4a742.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1b789a2028e8068fad522b48c8180a41.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9efc18a5bb2e53586331b2a58538a48b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/19f20f21a9d50b61dac519a3ddab539d.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/15/64b67707-b449-4dd2-8594-b179b9f1e727.png?resizew=203)
2022·上海杨浦·一模 查看更多[5]
2023届上海市杨浦区高三上学期一模物理试题(已下线)重难点10 电路与恒定电流-2023年高考物理【热点·重点·难点】专练(上海专用)(已下线)9.直流电路-2023年上海地区一模分类汇编上海市大同中学2023-2024学年高三上学期物理练习卷(二)上海市上海师范大学附属中学闵行分校2022-2023学年高二上学期期末考试物理试卷
更新时间:2022-12-15 02:21:16
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【推荐1】电源的两个重要参数是电动势E和内电阻r。对一个闭合电路有两种特殊情况;当外电路断开时,电源两端的电压等于电源电动势;当外电路短路时,短路电流等于电动势和内电阻的比值。现有一个电动势为E、内电阻为r的电源和一阻值为
的定值电阻,将它们串联或并联组成的系统视为一个新的等效电源,这两种连接方式构成的等效电源分别如图甲和乙虚线框所示,
、
和
、
分别为甲、乙等效电源的电动势和内阻。当这两个新的等效电源分别和一阻值为R的电阻连接时,新的等效电源输出功率恰好相等;若改为将
分别接在这两个新的等效电源两端,新的等效电源的输出功率分别为
、
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/522230546d4b802094e86ceb48c2ba38.png)
______
(选填“等于”“大于”、“小于”“无法判断”)
(2)![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2858005b9ae89ae080d83dcc13cf8e81.png)
______
(选填“等于”“大于”、“小于”、“无法判断”)
(3)![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2708fa6298e52f617383efc175b71ddc.png)
______
(选填“等于”、“大于”“小于”“无法判断”)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be9b4a83b9aebebf29de0c4406ebf894.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/522230546d4b802094e86ceb48c2ba38.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2858005b9ae89ae080d83dcc13cf8e81.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9b9cb8e6ff801523b0304576cd69fd2d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/522230546d4b802094e86ceb48c2ba38.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0b4f150ab98bde511e0f65d9bafab031.png)
(2)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2858005b9ae89ae080d83dcc13cf8e81.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2b3e95410f3b4fcb0cba425b521d1f67.png)
(3)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2708fa6298e52f617383efc175b71ddc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9b9cb8e6ff801523b0304576cd69fd2d.png)
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