15. A long conductive rod of radius R carries a nonuniform current density J(r) = J₀r/R, where J₀ is a constant and r is the radial distance form the rod axis. What is the expression for the magnetic field strength inside this rod?
(A) μ₀J₀r
(B) μ₀J₀r²/3R
(C) μ₀J₀r²/R
(D) μ₀J₀r²/5R
(E) None of the above.
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統計: A(0), B(1), C(0), D(0), E(0) #3858171
統計: A(0), B(1), C(0), D(0), E(0) #3858171
詳解 (共 1 筆)
#7434164
所以這題考的是長直導線內部磁場題
要用安培定律

因為是長圓柱導體,對稱性很好
因此可以得到

電流密度不是均勻的
所以我們要用積分


然後把它代回安培定律

ㅤㅤ
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