=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.
有一个函数=4pi (R)^2h,已知=4pi (R)^2h，=4pi (R)^2h，则V的计算结果的有效数字应取几位? （有一个函数,已知，，则V的计算结果
-3pi (R)^2-|||-C. -4pi (R)^2-|||-D. -5pi (R)^2
(B) dfrac (lambda )(2pi {varepsilon )_(0)a}. (C) dfrac (lambda )(4pi {varepsilon
C-|||-R-|||-+Q-|||-(B) dfrac (qQ)(4pi {varepsilon )_(0)R} , -dfrac (qQ)(4pi {var
dfrac (qQ)(4pi {varepsilon )_(0)l} C. dfrac (qQ)(2pi {varepsilon )_(0)l} D. -dfr
(B) dfrac (9)(4pi {varepsilon )_(0)a}-|||-(C) -dfrac (9)(8pi {varepsilon )_(0)a}
dfrac (qQ)(4pi {varepsilon )_(0)(d)_(1)} B. dfrac (qQ)(2pi {varepsilon )_(0)(d)_
17.-|||-设 (a,b)=(int )_(0)^2pi ((acos x-2bsin x))^2dx, 在 (a,b)leqslant 4pi 下,求使