【单选题】某平面简谐波在 t = 0.25s 时波形如图所示,则该波的波动方程为
A.
y = 0.5cos[4 p ( t - x /8) - p /2] (cm)
B.
y = 0.5cos[4 p ( t + x /8) + p /2] (cm)
C.
y = 0.5cos[4 p ( t + x /8) - p /2] (cm)
D.
y = 0.5cos[4 p ( t - x /8) + p /2] (cm)
【判断题】在源极耦合或射极耦合差分式放大电路中,源极或射极公共支路上的电流源动态电阻对共模输入信号来说相当于短路。
【单选题】某平面简谐波在t= 0.25s时波形如图所示,则该波的波函数为:【图片】
A.
y = 0.5cos[4 p ( t - x /8) - p /2] (cm)
B.
y = 0.5cos[4 p ( t + x /8) + p /2] (cm)
C.
y = 0.5cos[4 p ( t + x /8) - p /2] (cm)
D.
y = 0.5cos[4 p ( t - x /8) + p /2] (cm)
【简答题】本次实验中,实验箱上的 “ _________” 模块和 “ 可调信号发生器”模块产生信号
【单选题】在源极耦合或射极耦合差分式放大电路中,源极或者射极的公共支路采用恒流源是为了__________。
【单选题】Elizabeth Blackwell was born in England in 1821, and emigrated to New York City when she was ten years old. One day she decided that she wanted to become a doctor. That was nearly impossible for a wom...
A.
Because she couldn’t get admitted to medical school.
B.
Because she decided to further her education in Paris.
C.
Because a serious eye illness prevented her from doing so.
D.
Because it was difficult for her to start a practice in the United States.
【单选题】某平面简谐波在t= 0.25s时波形如图所示,则该波的波函数为:【图片】
A.
y = 0.5cos[4 π ( t - x /8) - π /2] (cm)
B.
y = 0.5cos[4 π ( t + x /8) + π /2] (cm)
C.
y = 0.5cos[4 π ( t + x /8) - π /2] (cm)
D.
y = 0.5cos[4 π ( t - x /8) + π /2] (cm)
【简答题】本次实验中,实验箱上的 “ ” 模块和 “ _________ ”模块产生信号