正弦电压<img src="https://nimg.ppkao.com/2018-08/lina/2018081916011565388.jpg?sign=9e1668bd1dbaff2227f52d5904a339c6&t=62d262ec" />,则正弦电压的有效值等于()。
A、
B、
C、Um
D、
A、
B、
C、Um
D、
A、A.<img src="https://img.ppkao.com/2018-08/lina/2018081916240013633.jpg" />
B.<img src="https://img.ppkao.com/2018-08/lina/2018081916240424865.jpg" />
C.<img src="https://img.ppkao.com/2018-08/lina/2018081916241135122.jpg" />
D.<img src="https://img.ppkao.com/2018-08/lina/2018081916241832814.jpg" />
A、A.<img src="https://img.ppkao.com/2018-08/longzhengxuan/2018081609061855082.jpg" />
B.<img src="https://img.ppkao.com/2018-08/longzhengxuan/2018081609062737698.jpg" />
C.<img src="https://img.ppkao.com/2018-08/longzhengxuan/2018081609063181144.jpg" />
D.<img src="https://img.ppkao.com/2018-08/longzhengxuan/2018081609063676713.jpg" />
A、A.S=P+Q
B.<img src="https://img.ppkao.com/2018-08/lina/2018083117500491800.jpg"/>
C.<img src="https://img.ppkao.com/2018-08/lina/2018083117500988874.jpg"/>
A、A.<img src="https://img.ppkao.com/2018-08/lina/2018083117233188591.jpg" />
B.<img src="https://img.ppkao.com/2018-08/lina/2018083117233741467.jpg" />
C.<img src="https://img.ppkao.com/2018-08/lina/2018083117234149944.jpg" />
D.<img src="https://img.ppkao.com/2018-08/lina/2018083117234896299.jpg" />
A、分析图示电路,当正弦交流电源电压有效值不变,而频率升高一倍时,各安培表的读数将怎样变化?为什么?
<img src="https://img.ppkao.com/2018-08/wenxueying/2018082909250061317.jpg" />
A、图示正弦交流电路中,电压u、u1、u2、u3的关系式可写为u=()。
<img src="https://img.ppkao.com/2018-08/lina/2018081917524036106.jpg" />
A、A.2
B.<img src="https://img.ppkao.com/2017-12/xieqiushi/2017120714483545055.jpg" />
C.<img src="https://img.ppkao.com/2017-12/xieqiushi/2017120714483937242.jpg" />
D.<img src="https://img.ppkao.com/2017-12/xieqiushi/2017120714484469853.jpg" />
A、A.<img src="https://img.ppkao.com/2017-10/wangjinchen/2017101309154866509.jpg" />低电平,<img src="https://img.ppkao.com/2017-10/wangjinchen/2017101309155838776.jpg" />三态,<img src="https://img.ppkao.com/2017-10/wangjinchen/2017101309155342124.jpg" />低电平
B.<img src="https://img.ppkao.com/2017-10/wangjinchen/2017101309154866509.jpg" />三态,<img src="https://img.ppkao.com/2017-10/wangjinchen/2017101309155838776.jpg" />低电平,<img src="https://img.ppkao.com/2017-10/wangjinchen/2017101309155342124.jpg" />高电平
C.<img src="https://img.ppkao.com/2017-10/wangjinchen/2017101309154866509.jpg" />低电平,<img src="https://img.ppkao.com/2017-10/wangjinchen/2017101309155838776.jpg" />高电平,<img src="https://img.ppkao.com/2017-10/wangjinchen/2017101309155342124.jpg" />高电平
D.<img src="https://img.ppkao.com/2017-10/wangjinchen/2017101309154866509.jpg" />高电平,<img src="https://img.ppkao.com/2017-10/wangjinchen/2017101309155838776.jpg" />低电平,<img src="https://img.ppkao.com/2017-10/wangjinchen/2017101309155342124.jpg" />高电平