【单选题】已知 下图( a )所示 单级电压放大电路 的输入电阻 R i =2kΩ ,输出电阻 R o =50kΩ ,开路电压增益 Avo =200 。当输入信号源内阻 R s =1kΩ ,输出负载电阻 R L =10kΩ 时 ,则可确定该电压放大电路的源电压增益Avs 约为____ 。若将两级上述电压放大电路级联, R s 、 R L 不变,如 下图( b )所示,则总的源电压增益 约为 ____ 。正确...
【简答题】Questions 5 to 7 are based on the news report you have just heard. 5. A ) It stayed in the air for about two hours . B ) It took off and landed on a football field . C ) It proved to be of high commer...
【简答题】直流电源电路如图所示,稳定电压为 6V , 1 )设电路正常工作,当电网电压波动而使 U I 增大时(负载不变),则 I R 将 ____ , I Z 将 ____ ,当负载电流增大时(电网电压不变),则 I R 将 ____ , I Z 将 ____ ; 2 )若负载电阻的变化范围为 200 Ω ~600 Ω ,则稳压管最大稳定电流与最小稳定电流之差应大于 ____ 。 3 )已知 U I =2...