Theory

 

Appendix B - Constants

Table 8 Constants of Free Space

Constant

Symbol

Value
Velocity of light

c

» 3.108 [m/s]
Permittivity

e 0

» [F/m]
Permeability

m 0

[H/m]
Intrinsic impedance

h 0

» 120p or 377 [W ]

Table 9 Physical Constants

Constant

Symbol

Value
Rest mass of electron

me

9.107.10-31 [kg]
Charge of electron

-e

-1.602.10-19 [C]
Charge-to-mass ratio of electron

-e/me

-1.759.1011 [C/kg]
Radius of electron

Re

2.81.10-15 [m]
Rest mass of proton

mp

1.673.10-27 [kg]

Table 10 Relative Permittivities (average low-frequency values at room temperature)

Material Value Material Value
Air 1.0 Plexiglas 3.4
Bakelite 5.0 Polyethylene 2.3
Glass 4-10 Polystyrene 2.6
Mica 6.0 Porcelain 5.7
Oil 2.3 Rubber 2.3-4.0
Paper 2-4 Soil 3-4
Paraffin wax 2.2 Teflon 2.1

Table 11 Relative Permeability's (average low-frequency values at room temperature)

Material Value Material Value
Ferromagnetic:   Diamagnetic:  
Nickel

250

Bismuth

0.99983

Cobalt

600

Gold

0.99996

Iron

4000

Silver

0.99998

Mumetal

100000

Copper

0.99999

Paramagnetic:      
Aluminum

1.000021

   
Magnesium

1.000012

   
Palladium

1.00082

   
Titanium

1.00018

   

Table 12 Conductivities (average low-frequency values at room temperature)

Material Value [S/m] Material Value [S/m]
Silver 6.17.107 Distilled water 2.10-4
Copper 5.80.107 Dry soil 10-5
Gold 4.10.107 Transformer oil 10-11
Aluminum 3.54.107 Glass 10-12
Brass 1.57.107 Porcelain 2.10-13
Bronze 107 Rubber 10-15
Iron 107 Fused quartz 10-17

Table 13 Ground Conductivity and Dielectric Constants

Surface Type Dielectric Constant Conductivity [S/m] Comment
Salt water

81

5.0

Excellent Ground
Fresh water

80

0.001

 
Pastoral, low hills, rich soil type

20

0.03

Very good
Flat country, marchy, densely wooded

13

0.007

 
Pastoral, medium hills, few trees

13

0.006

 
Pastoral, heavy clay soil

13

0.005

Average
Rocky soil, steep hills, mountainous

12

0.002

Poor
Sandy, dry, flat

10

0.002

 
Cities

5

0.001

Very poor
Cities, high buildings, industrial areas

3

0.001

 

 

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EMC of Telecommunication Lines
A Master Thesis from the Fieldbusters © 1997
Joachim Johansson and Urban Lundgren