1.lightning strikes a lossy dielectric sphere with ε=2.0ε0，電導係數=10(S/m) of radius 10 cm at t=0，depositing uniformly in the sphere a total charge 1(mC) .Determine，for all t,(a) the electric field intensity both inside and outside the sphere. (b) the current density in the sphere. (ε0=8.854*10^-12 F/m)
2.A current I flows in the inner conductor of an infinitely long coaxial line and returns via the outer conductor. The radius of the inner conductor is a,and the inner and outer radii of the outer conductor are b and c, respectively. Find the magnetic flux density B for all regions and plot B(絕對值) versus r.
3.A long dielectric cylinder of radius b and dielectric constant εr is placed along the
z-axis in an initially uniform electric field E0=ax E0. Determine V (r, Φ) and E(r, Φ)
both inside and outside the dielectric cylinder.
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