Physics

Difference Between Resistance and Resistivity

Main difference

The main difference between resistance and resistivity is that resistance opposes the flow of current and free electrons whereas resistivity describes the resistance of the specific material having a particular dimension.

Resistance vs Resistivity

Resistance is a specific property of a material that creates obstacles in the flow of current; Conversely, resistivity is a particular resistance that has specific dimensions. The resistance in a conductor is generally the ratio of the potential difference of the current passing through it, while the resistivity is usually the ratio of the strength of the electric field to the current density present at a particular temperature. The unit of resistance is measured in ohms (Ω), while the unit of resistivity is usually measured in ohmmeters (Ωm). The resistor symbol is R; instead, the resistivity symbol is ρ.

Resistance is considered as a property of a specific object and will be determined by the temperature, the material of the object, along with its dimensions (directly proportional to length, inversely related to cross section in a constant metal wire); On the other hand, resistivity is usually a property of a specific material and is independent of dimensions, but it is dependent on temperature and the material of the conductor. The formula for resistance is written as R=V/I or R=ρ(L/A); on the other hand, the formula for resistivity is written as ρ = (R × A) / L.

Resistance property applications in daily life are used in various places and things like fuses, heaters, sensors, etc.; On the other hand, electrical resistivity measurement applications are involved in calcareous soils and a quality control test. The resistor is always connected to the specific conductor; On the other hand, resistivity is usually related to the material of the conductor.

Comparison table

Endurance Resistivity
The property of a substance that opposes the flow of current is known as resistance. The resistivity of 1 m 3 of a substance is equal to the specific resistance.
Ratio of
The relationship between the potential difference across it and the current passing through it The relationship between the strength of the electric field and the current density present at a particular temperature.
Unit
The unit of resistance is ohms (Ω) The unit of resistivity is ohms (Ω m)
symbols
The resistance symbol is R The resistivity symbol is ρ
Considered as
Considered as a property of a specific object and determined by the temperature, the material of the object, along with its dimensions. Usually a property of a specific material.
temperature dependence
Depends on the temperature It depends on the temperature and the material of the conductor.
dimension dependency
Depends on the dimension Does not depend on the dimension
Dependence of length and cross-sectional area
Directly proportional to length, inversely related to cross section in a constant metal wire It does not depend on the length and cross-sectional area of ​​the conductor.
Formula
R = V / I or R = ρ (L / A) ρ = (R × A) / L
connection with conductor
Always connected to the specific driver Generally linked with the material of the conductor.
Applications
Applications of resistance property in daily life are used in various places and things like fuses, heaters, sensors, etc. Applications of electrical resistivity measurement are involved in calcareous soils and a quality control test.

What is the Resistance?

The term resistance is used in conductors and it acts as an obstacle in the flow of current or free electrons that are present in a conductor. The resistance (R) in a conductor is generally the ratio of the potential difference (V) to the current (I) that passes through it. It is mathematically written as R=V/I or R=ρ(L/A).

Where, l – length of the conductor, a – cross-sectional area of ​​the conductor, ρ – resistivity of the material. When the flow of charges occurs in a conductor, the flow of electrical current begins to travel. When a current flows through a wire, it looks like water flowing in a water pipe, and when the voltage drops in the wire it is similar to the pressure drop that drives the water down the pipe.

For example, consider electric current flowing in a uniform piece of cylindrical wire as a result of potential difference. When this flow of electrons occurs in an electrical wire, the atoms present in the wire vibrate their nuclei and very repeatedly knock the electrons out of their flow path and produce heat and this opposition results in the appearance of resistance. The longer the cylinder, the additional charge collisions with its atoms will occur.

The unit of resistance is measured in ohms and is usually represented as Ω in kΩ. Resistance is directly proportional to diameter, so the greater the width of the cylinder, the more current it can take. Different materials have different resistance to charge movement in the conductor.

The direction of the current is indicated by I on the side with an arrow symbol and it generally flows with the flow of positive charge and flows opposite to the flow of negative charges. So it means that resistance is present where current flows in the conductor in the direction of positive charges. Applications of resistance property in daily life are used in various places and things like fuses, heaters, sensors, etc.

The resistance through a wire rope is directly proportional to the length and inversely related to the cross section of a constant wire rope.

Factors Affecting Resistance

  • Cable resistance generally increases with increasing conductor length.
  • Resistance is inversely proportional to the cross-sectional area of ​​the metallic conductor.
  • Resistors rest on the material of the wire.
  • The resistance of the material usually depends on its temperature.
  • Small wires usually have a lower resistance; Large wires have high resistance.
  • Various materials develop superconductors when these materials drop below a critical temperature that offers zero resistance to current flow in the conductor.

What is resistivity?

The term resistivity is a particular resistance that has specific dimensions. The two particular situations and when associated, form a resistivity equation that is like ρ = (R × A) / L

Where ρ is the constant (known as the Greek letter “rho”) called the resistivity of the material, l – length of the conductor, a – cross-sectional area of ​​the conductor and R – Resistance of the material. Resistivity is usually a property of a specific material and is independent of dimensions, but it is dependent on temperature and the material of the conductor.

Resistivity is usually the ratio of the electric field strength (E) to the current density (J) present at a particular temperature, written as ρ = E/J. The unit of resistivity is usually measured in ohmmeters (Ωm) and R symbolizes it. The resistivity through a metallic wire is directly proportional to the temperature of the material and is independent of dimensions.

Factors that affect resistivity are included as the resistivity of a conductor increases with an increase in its temperature and the resistivity of a conductor decreases with a decrease in temperature. Some resistivity applications are used in calcareous soils and a quality control test.

Key differences

  1. One property that creates obstacles to the flow of free electrons and current is often resistance; conversely, a particular resistance having the specified dimensions is given by the resistivity.
  2. Resistance is tied to the specific conductor; on the other hand, the resistivity is related to the material of the conductor.
  3. In a conductor, resistance is the ratio of the potential difference through which current passes, while resistivity is usually the ratio of the electric field strength to the current density that occurs at a specific temperature.
  4. The unit of resistance is ohms (Ω), while the unit f of resistivity is commonly ohmmeters (Ωm).
  5. The resistor symbol is R; instead, the resistivity symbol is ρ.
  6. Resistance is directly proportional to length and inversely related to cross section in a constant metal wire; on the other hand, the resistivity depends on the temperature of the metal wire, but is independent of the dimensions.
  7. Resistance is determined by the temperature, the material of the object, along with its dimensions and is considered as a property of a specific object; on the contrary, resistivity is normally a specific property of a specific material.
  8. The formula for resistance is written as R=V/I or R=ρ(L/A); on the other hand, the formula for resistivity is written as ρ = (R × A) / L.
  9. The applications of resistor in daily life is that it is used in various places and things like fuses, heaters, sensors, etc.; on the other hand, the applications of electrical resistivity are that it intervenes in calcareous soils and a quality control test.

Final Thought

The above discussion concludes that resistance opposes the flow of current and free electrons and is directly dependent on dimension and cross-sectional area or length, while resistivity is the resistance of the specific material having a particular dimension but independent of dimension. , depending on the temperature.

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