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

dfrac (q)(4pi varepsilon oR)-|||-C. dfrac (q)(4pi {varepsilon )_(0)(R)^2}-|||-D.

=dfrac (Q)(4pi {varepsilon )_(0)r}-|||-(D) =dfrac (Q)(4pi {varepsilon )_(0)(r)^2

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

(int )_(-pi )^pi sqrt ({pi )^2-(x)^2}dx= )(int )_(-pi )^pi sqrt ({pi )^2-(x)^2}d

sqrt (2)pi :2 C. sqrt (2)pi :4 D. sqrt (2)pi :8

dfrac (pi )(4) C. dfrac (pi )(2) D.π

dfrac (1)(2)pi (R)^2E-|||-D. sqrt (2)(R)^2E-|||-E. dfrac (pi {R)^2E}(sqrt {2)}

dfrac (1)(2)pi .-|||-C.π-|||-D. dfrac (5)(4)pi .-|||-0

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

dfrac (qQ)(4pi {varepsilon )_(0)l} C. dfrac (qQ)(2pi {varepsilon )_(0)l} D. -dfr