1. CONDUCTOR PROPERTIES UNDER STATIC CONDITIONS
LECTURE # 14
CONDUCTOR PROPERTIES UNDER STATIC CONDITIONS

2. OBJECTIVES
To understand what happens to excess free charge in a conductor when exposed to external electric field.
To list down various conductor properties that under static conditions.

3. MODEL E applied P dQ Conductor
Point form of the continuity of current equation
Point form of Ohm’s law P dQ
Point form of Gauss’s law
Conductor
Simple partial differential equation

4. SOLUTION TO PARTIAL DIFFERENTIAL EQUATION
At point P
Charge density at t = 0 rv
Relaxation time
constant
rv0
Initial value at P
For conductor t

5. ANALYSIS E net = E applied – E induce +rs E induce - rs E applied
E induce
- rs
E applied
E net = E applied – E induce
Equipotential
body

6. CONDUCTOR PROPERTIES UNDER STATIC CONDITION
The net rv = 0 inside the conductor.
The net E = 0 inside the conductor.
The conductor is an equipotential body.
Charge density rs, if present, is found only on the surface.

7. EXAMPLE 14.1
Find the magnitude of the electric field intensity in a sample of silver having s = 6.17 x 107 mho/m and me = m2/V.s if (i) the drift velocity is 1 mm/s; (ii) the current density is 107 A/m2; (iii) the sample is a cube, 3mm on a side, carrying a total current of 80 A; (iv) the sample is a cube, 3 mm on a side, having a potential difference of 0.5 mV between opposite faces.

8. EXAMPLE 14.2
An aluminum conductor is 1000 ft long and has a circular cross section with a diameter of 0.8 in. If there is a dc voltage of 1.2 V between the ends, find: (i) the current density; (ii) the current; (iii) the power dissipated, using your vast knowledge of circuit theory.

9. THANK YOU
QUESTIONS AND ANSWERS