A.Listen to the short dialogues and choose the best answer to each question you have heard. Both the dialogues and the questions will be spoken only once. 2
【简答题】三、在图示电路中, 已知 V CC = 12V ,晶体管的 b = 100 , R’ b = 100k Ω 。填空:要求先填文字表达式后填得数。 ( 2 )若测得输入电压有效值 =5mV 时,输出电压 有效值 Uo ’ = 0.6V , 则电压放大 倍数: Au = ≈ 。 若负载电阻 R L 值与 R C 相等 ,则带上负载 后输出电 压有效值 U O = = V