Resistivity Temperature Dependence

The resistance of a conductor is a measurement of the conductor’s resistance to current flow. The resistance to current flow varies between conductors.

The letter R stands for resistance. A conductor’s resistance, R, is defined as the ratio of the potential difference, V, across it to the current, I, flowing through it.The ohm is the SI unit for resistance. The ohm is represented by the Greek letter omega . Resistance is measured in scalar units.When a potential difference of 1 volt is put across the ends of a conductor, it produces a current of 1 ampere to flow through it.

Temperature dependence of resistivity:

• When the temperature of a metal or conductor rises, the metal’s resistivity rises, and thus the current flow in the metal decreases. They have a temperature coefficient that is positive. It has a positive value.

• When the temperature of a semiconductor is raised, the material’s conductivity increases. It signifies that the material’s resistivity is reduced, and thus the current flow is increased. Semiconductors have a negative temperature coefficient of efficiency. As a result, the temperature coefficient of resistivity has a negative value.

• When the temperature of an insulator is raised, the material’s conductivity increases. We know that as the conductivity of a material increases, the resistivity drops, and the current flow increases.As a result, some insulators that are insulators at ambient temperature become conductors at high temperatures. Insulators have a negative temperature coefficient of efficiency. The temperature coefficient of resistivity has a negative value.When the temperature of a material is raised, the atoms vibrate, causing the valence electrons in the valence band to move into the conduction band. As a result, the material’s conductivity improves. When a material’s conductivity rises, the resistance falls, and the current flow rises. As a result, some insulators that are insulators at ambient temperature become conductors at high temperatures.

• Superconductors are materials that have no resistance. The critical temperature is the temperature at which the resistance reduces to zero. The property of superconductivity of a material will be loosened by high temperature, strong magnetic field, and high current density. A super conductor is something like mercury. The magnetic field bends around the superconductor when it is placed in it because it does not allow the magnetic field to pass through it. When the magnetic field’s intensity is increased, the field is able to pierce through the superconductor at a specific point, and the super conductor’s behaviour is destroyed.Consider passing an electric current through a superconductor. If the current density is raised, it loses its superconductivity and eventually behaves like a regular material at a certain current density. The critical current density is the current density at which a material loses its superconductivity.The behaviour of superconductivity in a material is destroyed by high temperature, strong magnetic field, and high current density. These materials are now often used in MRI equipment.

• The resistivity of materials like nichrome, manganin, and constantan is relatively low and does not vary greatly with temperature. As a result, these materials are employed in wire-bound standard resistors since the difference in resistance value when the temperature changes is negligible.

• The resistivity is affected by a number of parameters, including the time it takes for collisions to relax and the charge density. It is obvious from the preceding scenarios that when the temperature rises, the average speed of the electrons rises, resulting in more collisions. As a result, the period between impacts slows down. In the case of metals, the charge density is mostly independent of temperature.

Tungsten resistivity temperature dependence:

A basic light bulb is made up of a thin tungsten wire that absorbs all of the electricity. (In a closed circuit, the wire has the highest resistance.) The electrical energy is subsequently converted to heat, which can heat the wire up to 3600 degrees Fahrenheit. The wire begins to radiate in the visible spectrum (blackbody radiation) at these temperatures, which humans perceive as light creation. The resistance of the tungsten wire, on the other hand, varies between ambient temperature and 3600 K.

Temperature dependence and measurement of resistivity of pure water:

Temperature has a big impact on the conductivity or resistivity of clean water with no contaminants. The conductivity changes by roughly 7% per degree Celsius at low temperatures near to 0°C. It is critical to implement pure water temperature adjustments.

Conclusion:

The nature of a substance that enables or resists the flow of electric current through a certain element or material is referred to as resistivity. The temperature dependence of electrical resistance is one of the most startling aspects of resistivity! It’s difficult to fathom how an element’s temperature affects the degree of conductivity of a substance, but believe it or not, this is science, and it happens virtually every day, all around us.