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? （

=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.

-3pi (R)^2-|||-C. -4pi (R)^2-|||-D. -5pi (R)^2

(4pi^2)注 类似地，圆盘$(x-2)^{2}+y^{2}\leqslant 1$绕y轴旋转而成的旋转体的体积为_____. $(4\pi^{2})$

C-|||-R-|||-+Q-|||-(B) dfrac (qQ)(4pi {varepsilon )_(0)R} , -dfrac (qQ)(4pi {var

17一个未带电的空腔导体球壳,内半径为R。在腔内离球心的距离为d处 -|||-A、 .-dfrac (9)(4pi {varepsilon )_(0)R}-||

(B) .dfrac ({mu )_(0)I}(2pi R)+dfrac (3{mu )_(0)I}(8R)-|||-(c) dfrac ({mu )_(0)I

_(1)lt rlt (R)_(2) =dfrac ({Q)_(1)}(4{{Te)_(0)(r)^2}}-|||-D.两球面间的电势差 Delta U=dfr

(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