106年 - 106 國立中山大學_碩士班招生考試_電機系(戊組)、電波領域：電磁學#110197

1.(20%) The radius of the solid inner conductor and the inner radius of the very thin outer conductor of an air coaxial transmission line are r_i and r_o, respectively. A uniform current I flows in the inner conductor and returns via the thin outer conductor in the other direction. The permeability of free space μ₀ is H/m. Determine the stored magnetic energy per unit length of the line.

2.(20%) Determine the capacitance of a spherical capacitor with an inner conducting sphere of radius a and an outer conductor of radius b. The permittivity of a dielectric medium between these two concentric spherical conductors is ε.

(a) (6%) Findε₂ in terms of ε₀.