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Specific resistance (at 20° C)

Substance Resistance level, μOhm - mm2/m
Aluminum 0,028
Tungsten 0,055
Iron 0,098
Gold 0,023
Constantan 0,44-0,52
Brass 0,025-0,06
Manganine 0,42-0,48
Copper 0,0175
Molybdenum 0,057
Nickelin 0,39-0,45
Nickel 0,100
Tin 0,115
Mercury 0,958
Lead 0,221
Silver 0,016
Tantalum 0,155
Fechral 1,1-1,3
Chromium 0,027
Zinc 0,059
Substance К Substance К
Aluminum 0,0042 Tin 0,0042
Tungsten 0,0048 Platinum 0,004
Constantan 0,2 Mercury 0,0009
Brass 0,001 Lead 0,004
Copper 0,0043 Silver 0,0036
Manganine 0,3 Steel 0,006
Molybdenum 0,0033 Tantalum 0,0031
Nickel 0,005 Chromium 0,006
Nickelin 0,0001 Fechral 0,0002
Nichrome 0,0001 Zinc 0,004

Resistance alloys

  • Constantan (58.8 Cu, 40 Ni, 1.2 Mn)
  • Manganine (85 Cu, 12 Mn, 3 Ni)
  • Neusilber (65 Cu, 20 Zn, 15 Ni)
  • Nickel (54 Cu, 20 Zn, 26 Ni)
  • Nickel (67.5 Ni, 15 Cr, 16 Fe, 1.5 Mn)
  • Reonate (84Cu, 12Mn, 4 Zn)
  • Fechril (80 Fe, 14 Cr, 6 Al)

Nichrome specific resistance

Let us consider the electronic theory of this phenomenon. As free electrons move through a conductor, they constantly encounter other electrons and atoms in their path. Interacting with them, the free electron loses part of its charge. Thus, the electrons encounter resistance from the material of the conductor. Each body has its own atomic structure, which offers different resistance to electric current. The unit of resistance is taken to be ohms.

The resistance of each individual conductor (denoted by R or r.) depends on the properties of the material from which it is made. In order to accurately characterize the electrical resistance of a particular material, the notion of specific resistance (nichrome, aluminum , etc.) was introduced. Specific resistance is the resistance of a conductor up to 1 m long, with a cross-section of 1 sq. mm. This value is denoted by the letter p. Each material used in the manufacture of a conductor has its own specific resistance. For example, consider the resistivity of nichrome and fahl.

  • X15N60 - 1.13 Ohm*mm2/m
  • X23Yu5T - 1.39 Ohm* mm2/m
  • X20N80 - 1.12 Ohm* mm2/m
  • CrN70U - 1.30 Ohm* mm2/m
  • CrN20US - 1.02 Ohm* mm2/m

Application

High level of specific resistance of nichrome and fechral allows to use these materials in the production of heating elements. The most common products are nichrome filament, ribbon, strip X15N60 and X20N80 as well as X23NU5T ferrule wire for heating devices, household appliances and electric heating elements of industrial furnaces.