【判断题】
电阻并联时,其总电阻值比任何一个分电阻值都小。
A. 对
B. 错
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答案
A
解析
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【判断题】
没有兆欧表时,可以用万用表测量绝缘电阻值。
A. 对
B. 错
【判断题】
硅可控整流元件是一种新型大功率半导体器件,习惯上称它为可控硅。
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【判断题】
电荷之间存在相互作用力,同性电荷互相吸引, 异性电荷互相排斥。
A. 对
B. 错
【判断题】
导电能力介于导体和绝缘体之间的物质称为半导体.。
A. 对
B. 错
【判断题】
电流不经负载而由电源一端直接回到电源另一端,导致电路中电流猛烈加大,这就叫断路。
A. 对
B. 错
【判断题】
一般金属导体如铜和铝等,电阻是随温度升高而减小。
A. 对
B. 错
【判断题】
日常用的电炉,电烙铁,电烘箱等都是使用电流热效应来制成的电器。
A. 对
B. 错
【判断题】
变压器是利用互感现象来制作的。
A. 对
B. 错
【判断题】
直流电可以通过变压器变换电压
A. 对
B. 错
【判断题】
功率因数是交流电路中有功功率与无功功率的比值。
A. 对
B. 错
【判断题】
变压器不装铁芯也行。
A. 对
B. 错
【判断题】
变压器油有绝缘作用。
A. 对
B. 错
【判断题】
常用安全电压为:36,24,12伏三种。
A. 对
B. 错
【判断题】
容量在2千伏安以下的单相变压器称为小型变压器。
A. 对
B. 错
【判断题】
兆欧表属于感应式测量仪表。
A. 对
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【填空题】
1、欧姆定律表明,电路中电阻不变时电流与___成正比,电路中电压不变时电流与___成反比。
【填空题】
2、R1、R2、R3三个电组串联后接到电压为U的电源上,则该电路的总电流为___)。
【填空题】
3、某直流负载两端电压为12V,其电流为8A,该负载电阻为___。
【填空题】
4、220V、100W的电烙铁其电阻应为___。
【填空题】
5、一条电阻值为80Ω的电阻丝,对折后并联测量,其电阻值应为___。
【填空题】
6、我国电力系统中,交流电的频率为___ ,周期为___。
【填空题】
7、交流电的三要素是___。
【填空题】
8、正弦交流电的频率为50HZ,则角频率为___。
【填空题】
9、正弦交流电的最大值是311V,其有效值为___。
【填空题】
10、有一单相正弦电压u=311sin___V,其最大值为___,初相位为___。
【填空题】
11、R=6Ω的纯电阻与Xc=8Ω的纯容抗相串联,其等效阻抗为___。
【填空题】
12、R=9Ω的纯电阻与XL=8Ω的纯___抗相串联,其等效阻抗为___。
【填空题】
13、三相交流电为了区别相位,用统一规定的颜色来表示,我国规定用黄色表示A相,用___色表示B相,用___表示C相。
【填空题】
14、在交流电路中,电源提供的电功率有两种:一种是___功率,另一种是有功功率。
【填空题】
15、测量电流应使用___,并将其___在电路中。
【填空题】
16、为保证测量的准确,电流表的内阻应尽可能地___。
【填空题】
17、为保证测量的准确,电压表的内阻应尽可能地___。
【填空题】
18、测量线路中的电流,但又不能中断负载的运行,应选用___的电流表。
【填空题】
19、万用表用毕,应将转换开关拨至交直流___或OFF档。
【填空题】
20、通过人体工频电流的有效值约为___时,会有触电的感觉,此值称为___电流。
【填空题】
21、通过人体工频电流的有效值约为___时,触电者能自主地摆脱电源,此值称为___电流。
【填空题】
22、通过人体工频电流的有效值达到___时,有可能引起心室纤维颤动,这是___的主要原因。
【填空题】
23、触电事故发生的季节性表现在:___季比___季多,以___月份为最多。
【填空题】
24、保护接地适用于电源中性点___的三相三线配电网。
【填空题】
25、常用的低压基本安全用具有___。
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