已知电场的复数为 bar(E)=40(sqrt(2)-jsqrt(2))e^-j20zvec(e)_x，其瞬时表达式为A. bar(E)=80cos(omega t-20z-(pi)/(4))vec(e)_xB. bar(E)=80cos(omega t-20z+(pi)/(4))vec(e)_xC. bar(E)=80cos(omega t-20z-(3pi)/(4))vec(e)_xD. bar(E)=80cos(omega t-20z+(3pi)/(4))vec(e)_x

已知电场的复数为 $\bar{E}=40\left(\sqrt{2}-j\sqrt{2}\right)e^{-j20z}\vec{e}_x$，其瞬时表达式为

A. $\bar{E}=80\cos\left(\omega t-20z-\frac{\pi}{4}\right)\vec{e}_x$

B. $\bar{E}=80\cos\left(\omega t-20z+\frac{\pi}{4}\right)\vec{e}_x$

C. $\bar{E}=80\cos\left(\omega t-20z-\frac{3\pi}{4}\right)\vec{e}_x$

D. $\bar{E}=80\cos\left(\omega t-20z+\frac{3\pi}{4}\right)\vec{e}_x$