(B) (mu ,dfrac (1)(sqrt {2pi )})-|||-(C) (mu ,dfrac (1)(2)), (D)(0,σ).

dfrac ({mu )_(0)I}(pi R)(dfrac (1)(2)+dfrac (pi )(6))-|||-dfrac ({mu )_(0)I}(pi

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

sqrt (2)pi -|||-C. dfrac (sqrt {2pi )}(4)-|||-D. dfrac (sqrt {2pi )}(8)

(D) =dfrac ({mu )_(0)(I)_(1)(I)_(2)}(2pi )ln dfrac (b)(a)-|||-Ai-|||-I1-|||-C I2

. _(Y)(y)=dfrac (1)(2sqrt {2pi )}(e)^-dfrac (y{2)} ,gt 0-|||-bigcirc ._(Y)(y)=d

dfrac (qQ)(4pi {varepsilon )_(0)(d)_(1)} B. dfrac (qQ)(2pi {varepsilon )_(0)(d)_

dfrac (2pi )(sqrt {3)} D. dfrac (pi )(6)

dfrac (2pi )(sqrt {3)}-|||-D. dfrac (pi )(6)

._(M)-(U)_(N)= -dfrac ({mu )_(0)lg g}(2pi )tln dfrac (a+l)(a) ___ o

(B) dfrac (lambda )(2pi {varepsilon )_(0)a}. (C) dfrac (lambda )(4pi {varepsilon