Answer Happy

1. A coaxial cable has a thin conducting copper wire at the
centre of the cable, positively charged with linear charge density
 = 9.0 x 10-9 C/m. It has a rubber coating (dielectric constant r
= 2.0, relative permeability r = 3.8) of inner radius a = 0.5 mm
and outer radius b = 0.9 mm, and an air gap exist between the core
wire and the rubber coating. (see Figure 1).
Figure 1. Coaxial copper cable geometry
(a). Calculate the electric field magnitude (with correct unit)
at radial distance from the copper wire r = 0.3 mm (air). Use three
significant figures.
(b). Calculate the electric field magnitude (with correct unit)
at radial distance from the copper wire r = 0.8 mm (rubber). Use
three significant figures.
(c). Calculate the electric field magnitude (with correct unit)
at radial distance from the copper wire r = 1.4 mm (air). Use three
significant figures.
(d). Plot the magnitude of the E field E(r) with respect to r,
from 0 to r = 1.4 mm, specifying all the discontinuities. [4]
(e). Based on the results in (d), plot a qualitative potential
function V(r) with respect to r, from r = 0.3 mm to r = 1.4 mm,
with reference 0 V at r =1.4 mm, i.e., V(r =1.4 mm) = 0. [4]
λ (C/m) Rubber- L