研究所、轉學考(插大)◆普通物理學題庫下載題庫

(14)Helmholtz coils are sometimes used to obtain a nearly uniform magnetic field in situations where a solenoid would be impractical as shown in the right figure. The magnetic field at the center point on the axis, midway between the coils, how about the derivative of B?
(A)B(x) ≈ B₀ + B'(0)x
(B)B(x) ≈ B₀ + B''(0)x²
(C)B(x) ≈ B₀ + B'''(0)x³
(D)B(x) ≈ B₀ + B''''(0)x⁴
(E)B(x) ≈ B₀ + B'''''(0)x⁵