Principle of Water Content Test of Insulating Oil
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Electrical Engineering Materials
What is an Atom?
Atomic Energy Levels
Classification of Engineering Materials
Classification of Electrical Engineering Materials
Electron Configuration of Atom
Physical Properties of Materials
Mechanical Properties of Engineering Materials
Rutherford Atomic Model
Bohrs Atomic Model
Chemical Properties of Materials
Energy Bands in Crystals
Electrical Properties of Engineering Materials
Fermi Dirac Distribution Function
Magnetic Properties of Engineering Materials
Selection of Material for Engineering Application
Bases of existence of properties in materials
Low Resistivity or High Conductivity of Conducting Material
High Resistivity or Low Conductivity Conducting Material
Factors Effecting the Resistivity of Electrical Materials
Materials used for Heating Elements
Materials used for Precious Works
Materials Used for Transmission Line Conductor
Electrical Stranded Conductors
Materials used for Rheostats
Materials for Lamp Filaments
Classification of Electrical Conducting Material
Applications of Carbon Materials in Electrical Engineering
Selection of Materials Used for Electrical Contacts
Mechanism of Polarization
Dielectric Material as an Electric Field Medium
Electric Arc Furnace
Thermal Conductivity of Metals
Free Electron Theory of Metals
Thomson Plum Pudding Model (1911)
Factors Effecting the Resistivity of Electrical Materials
- Mechanical stressing.
- Age Hardening.
- Cold Working.
α1 is temperature coefficient of resistance of material at temperature of t1o C If the value of α1 is positive, the resistivity of material is increase. The resistivity of metals increase with increase of temperature. Means the metals are having positive temperature coefficient of resistance. Several metals exhibit the zero resistivity at temperature near to absolute zero. This phenomenon is “called the superconductivity”. The resistivity of semiconductors and insulators decrease with increase in temperature. Means the semiconductors and insulators are having negative temperature coefficient of resistance. Alloying Alloying is a solid solution of two or more metals. Alloying of metals is used to achieve some mechanical and electrical properties. The atomic structure of a solid solution is irregular as compared to pure metals. Due to which the electrical resistivity of the solid solution increases more rapidly with increase of alloy content. A small content of impurity may increase the resistivity metal considerably. Even the impurity of low resistivity increases the resistivity of base metal considerably. For example the impurity of silver (having lowest resistivity among all metals) in copper increase the resistivity of copper.
Mechanical stressing Mechanical stressing of the crystal structure of material develops the localized strains in the material crystal structure. These localized stains disturb the movement of free electrons through the material. Which results in an increase in resistivity of the material. Subsequently, annealing, of metal reduces the resistivity of metal. Annealing of metal, relieve the mechanical stressing of material due to which the localized stains got removed from the crystal structure of the metal. Due to which the resistivity of metal decrease. For example, the resistivity of hard drawn copper is more as compared to annealed copper. Age Hardening Age hardening is a heat treatment process used to increase the yield strength and to develop the ability in alloys to resist the permanent deformation by external forces. Age hardening is also called “Precipitation Hardening”. This process increases the strength of alloys by creating solid impurities or precipitate. These created solid impurities or precipitate, disturb the crystal structure of metal which interrupts the flow of free electrons through metal/Due to which the resistivity of metal increases. Cold Working Cold working is a manufacturing process used to increase the strength of metals. Cold working is also known as “Work hardening” or “Strain hardening”. Cold working is used to increase the mechanical strength of the metal. Cold working disturbs the crystal structure of metals which interfere with the movement of electrons in metal, due to which the resistivity of metal increases.
Closely Related Articles Electrical Engineering MaterialsWhat is an Atom?Atomic Energy LevelsClassification of Engineering MaterialsClassification of Electrical Engineering MaterialsElectron Configuration of AtomPhysical Properties of MaterialsMechanical Properties of Engineering MaterialsRutherford Atomic ModelBohrs Atomic Model Chemical Properties of MaterialsEnergy Bands in CrystalsElectrical Properties of Engineering MaterialsFermi Dirac Distribution FunctionMagnetic Properties of Engineering MaterialsThermionic EmissionSelection of Material for Engineering ApplicationBases of existence of properties in materialsQuantum NumbersLow Resistivity or High Conductivity of Conducting MaterialHigh Resistivity or Low Conductivity Conducting MaterialMaterials used for Heating ElementsMaterials used for Precious WorksMaterials Used for Transmission Line ConductorElectrical Stranded ConductorsElectrical ConductorMaterials used for RheostatsMaterials for Lamp FilamentsClassification of Electrical Conducting MaterialApplications of Carbon Materials in Electrical EngineeringSelection of Materials Used for Electrical ContactsBimetalsIonic PolarizationPiezoelectricityDielectric MaterialsMechanism of PolarizationDielectric Material as an Electric Field MediumOrientational PolarizationElectric Arc FurnaceThermal Conductivity of MetalsFree Electron Theory of MetalsMagnetostrictionAntiferroelectricityFerroelectric MaterialsElectronic PolarizationFerromagnetic MaterialsMore Related Articles Thomson Plum Pudding Model (1911)New Articles Principle of Water Content Test of Insulating OilCollecting Oil Sample from Oil Immersed Electrical EquipmentCauses of Insulating Oil DeteriorationAcidity Test of Transformer Insulating OilMagnetic Flux