(B) dfrac (9)(2pi {c)_(0)(y)^2} - y 个-|||-P(0,y)-|||-+q-|||-(C) dfrac (qa)(2pi {
U=0 (B) E=0 , =dfrac (9)(2pi {varepsilon )_(0)a} q q-|||-(C) =dfrac (q)(2pi {var
U=0-|||-(B) E=0 . =dfrac (q)(2pi {varepsilon )_(0)a}-|||-(C) =dfrac (q)(2pi {var
. _(Y)(y)=dfrac (1)(2sqrt {2pi )}(e)^-dfrac (y{2)} ,gt 0-|||-bigcirc ._(Y)(y)=d
(B) dfrac (lambda )(2pi {varepsilon )_(0)a}. (C) dfrac (lambda )(4pi {varepsilon
dfrac (qQ)(4pi {varepsilon )_(0)l} C. dfrac (qQ)(2pi {varepsilon )_(0)l} D. -dfr
dfrac (qQ)(4pi {varepsilon )_(0)(d)_(1)} B. dfrac (qQ)(2pi {varepsilon )_(0)(d)_
=dfrac (T)(2pi )leqslant [ t] =dfrac ([ O] )(2);-|||-_(2)(A)_(1)+dfrac ({M)_(y)}
(B) dfrac (9)(4pi {varepsilon )_(0)a}-|||-(C) -dfrac (9)(8pi {varepsilon )_(0)a}
1.一平面电磁波能表示成 _(x)=0, _(y)=2cos [ 2pi times (10)^14(dfrac (z)(c)-t)+dfrac (pi )(2