Unit Of Specific Resistance

What is specific resistance?

Specific resistance is defined as the resistance offered per unit length and unit cross-sectional area when the known amount of voltage is applied. The mathematical representation is as follows:

\(\rho =\frac{RA}{L}\)

Where,

⍴: specific resistance

R: resistance

A: cross-sectional area

L: length of the material

Specific resistance is the reciprocal of specific conductance, which is defined as a measure of a material’s ability to conduct electricity. The symbolic representation of specific conductance is 𝛋. It may also refer to:

  • Specific electric resistance
  • Specific airway resistance
  • Specific resistance due to friction for a mechanism transporting mass.
Material Specific resistance at 20 °C
Ohms
Silver 9.8
Copper 10.37
Gold 14.7
Tungsten 33.2
Steel 95.8

Unit of specific resistance

SI unit of specific resistance is ohm meter (Ωm)

What is electric resistivity?

Specific electrical resistance is also known as electric resistivity is a property of material defining how strongly can the material oppose the flow of electric current. SI unit of electrical resistivity is ohm-metre and is represented as ⍴.

What is airway resistance?

Airway resistance is studied in respiratory physiology and is defined as the resistance of the respiratory tract to airflow during inhaling and exhaling. Following is the formula similar to Ohm’s law:

\(R_{AW}=\frac{\Delta P}{\dot{V}}\)

Where,

\(\Delta P=P_{ATM}-P_{A}\) \(R_{AW}=\frac{P_{ATM}-P_{A}}{\dot{V}}\)

Where,

RAW: airway resistance

ΔP: pressure difference driving airflow

PATM: atmospheric pressure

PA: alveolar pressure

\(\dot{V}\) : volumetric airflow

Specific resistance of copper

The specific resistance of copper which is a good conductor is 1.72*10-8 ohm meter and the specific resistivity of air which is a poor conductor is 1.5*1014 ohm meter.

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