Question

How could we calculate the following:

1. Electric Flux Density in Dielectric

2. Electric Field in Dielectric

3. Electric field in the copper core

Given:

The cable is 10m long, center core's diameter is 2mm, the shield has inner diameter of 5mm. They are both made of copper. There is a shield that is held at +50 V and the center core is at 0 V. The relative permeability is 1.35

Answer 1

2) The two electrodes are maintained at a constant potential.

The electric field between them is given by

Where V is the potential difference between the electrodes and

d is the separation between them.

The direction of electric field is from higher potential to lower potential.

Here, V = (50-0) =  50 V

The direction is from shield to core.

d = 5 mm - 2 mm = 3 mm = 0.003 m

So,

E = 50/0.003 = 16666.67 V/m

1) The electric flux density is given by

here, the dielectric permittivity of the material is 1.35

So,

So,

3)

The copper core is a conductor.

No matter what the charge or potential it is at, the electric field inside a conductor is always zero.