U=0-|||-(B) E=0 . =dfrac (q)(2pi {varepsilon )_(0)a}-|||-(C) =dfrac (q)(2pi {var
(B) dfrac (9)(2pi {c)_(0)(y)^2} - y↑-|||-(0,y)-|||-+q-|||-(C) dfrac (qa)(2pi {va
(B) dfrac (9)(2pi {c)_(0)(y)^2} - y 个-|||-P(0,y)-|||-+q-|||-(C) dfrac (qa)(2pi {
(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 (Q)(4pi {varepsilon )_(0)r}-|||-(D) =dfrac (Q)(4pi {varepsilon )_(0)(r)^2
dfrac (q)(4pi varepsilon oR)-|||-C. dfrac (q)(4pi {varepsilon )_(0)(R)^2}-|||-D.
dfrac (qQ)(4pi {varepsilon )_(0)(d)_(1)} B. dfrac (qQ)(2pi {varepsilon )_(0)(d)_
C-|||-R-|||-+Q-|||-(B) dfrac (qQ)(4pi {varepsilon )_(0)R} , -dfrac (qQ)(4pi {var
(B) dfrac (9)(4pi {varepsilon )_(0)a}-|||-(C) -dfrac (9)(8pi {varepsilon )_(0)a}