6.在真空中沿着x轴正方向传播的平面电磁波,其电场强度波的波动方程是 _(z)=-|||-_(0)cos [ 2pi (vt-dfrac (x)(lambda ))] , 则其磁场强度波的波动方程是 ()-|||-(A) _(y)=-sqrt (dfrac {k{x)_(0)}({varepsilon )_(0)}}(E)_(0)cos [ 2pi (vt-dfrac (x)(lambda ))] (B) _(y)=sqrt (dfrac {{e)_(0)}({u)_(0)}}(e)_(0)cos [ 2pi (vt-dfrac (x)(lambda ))] -|||-(C) _(3)=-sqrt (dfrac {{e)_(0)}({mu )_(0)}}(e)_(0)cos [ 2pi (vt-dfrac (x)(lambda ))] (D) _(y)=-sqrt (dfrac {{e)_(0)}({x)_(0)}}_(0)cos [ 2pi (vt+dfrac (x)(lambda ))]